Production method of microlens array, liquid crystal display device and production method thereof, and projector

ABSTRACT

A method of producing a microlens array includes a patterning step of forming a first optical resin layer having a first refractive index on a transparent substrate and forming a plurality of microlens planes arrayed in a two-dimensional pattern on the front surface of the first optical resin layer; a planarizing step of forming a planarized second optical resin layer; a joining step of providing a support layer on which a transparent protective film is previously formed; and a removing step of removing the support layer in such a manner that only the protective film remains on the second optical resin layer. The planarizing step is performed by filling irregularities of the microlens planes with a resin having a second refractive index and planarizing the front surface, opposed to the microlens planes, of the resin, to form the planarized second optical resin layer, and the joining step is performed by joining the support layer to the planarized second optical resin layer. With this method, a microlens array excellent in surface accuracy and flatness can be produced without the need of provision of a support layer made from glass.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to a method of producing amicrolens array, a liquid crystal display device incorporating themicrolens array and a method of producing the liquid crystal displaydevice, and a projector using the liquid crystal display device as alight bulb.

[0002] Projectors using an LCD (Liquid Crystal Display Device), DMD(Digital Mirror Device), or LCOS (LC ON SILICON) as a light bulb hasbeen actively developed. From the viewpoints of function and shape,projectors are classified into a data projector mainly used for monitordisplay for personal computers, a front projector or a rear projectormainly used for AV for home theaters and the like, and a rear projectorfor TV. Meanwhile, from the viewpoint of the number of light bulbs,projectors are classified into a one-screen type, a two-screen type, anda three-screen type. The light bulbs are classified into a transmissiontype and a reflection type.

[0003] The higher luminance characteristics of projectors may berequired in the future. To meet such a requirement it is primarilyexpected to improve optics. For example, it is expected to enhance theluminance of a light source to be used, to shorten the arc length (forrealizing pointed light source) in the case of using an arc lamp, tooptimize optical members, and to miniaturize optical members.

[0004] To meet the above requirement, it is secondarily expected toincrease the aperture ratio of a light bulb as a key device of aprojector. In this case, it is basically required to realize a finerstructure and a higher aperture ratio of the device at the pixel level.If liquid crystal is used as an electro-optical medium, however, theaperture ratio of pixels cannot be enhanced only by providing a simplefine structure of the device. The reason for this is as follows: namely,since liquid crystal is a continuous body, a shielding black matrixhaving an area being large enough to prevent leakage of light fromreverse tilt domains and to prevent leakage of light of thin filmtransistors for driving the liquid crystal must be provided, with aresult that the aperture ratio of pixels are correspondingly sacrificed.

[0005] To improve the utilization efficiency of light emitted from alight source and also to enhance the luminance, an attempt has been madeto mount microlens arrays to liquid crystal display devices. Forexample, a flat display device incorporating a microlens array has beendisclosed in Japanese Patent Laid-open No. Hei 2000-206894. A microlensarray incorporated in a high precision liquid crystal display device(liquid crystal panel) for a related art liquid crystal projector hasbeen produced by using a glass substrate such as a quartz substrate or aneoceram glass substrate (hereinafter, the glass substrate used for amicrolens array is sometimes referred to as “cover glass”). To be morespecific, a method of forming a microlens array using the cover glass bya wet-etching or dry-etching process or a 2P (Photo-Polymerization)process has been put into practical use. In each case, a region in whicha microlens array is to be formed is composed of a transparent resin.The thickness of a cover glass for supporting such a transparent resinhas been reduced by polishing or grinding in a controlled manner, and atransparent conductive film (for example, ITO film) for a display devicehas been formed on the cover glass, as needed.

[0006] A related art method of producing a microlens array by using awet etching process will be described with reference to FIGS. 1A to 1D.

[0007] In a step shown in FIG. 1A, after a quartz substrate is cleaned,a resist is applied on the quartz substrate, and is patterned into apattern corresponding to an array pattern of pixels by exposure anddevelopment. In a step shown in FIG. 1B, the quartz substrate issubjected to isotropic etching via the resist, to form spherical lensplanes R. In addition, a film of a metal, polysilicon, or amorphoussilicon excellent in chemical resistance may be used as a mask in placeof the resist. The etching may be performed by using an HF or BHF basedetchant.

[0008] In a step 1C, a cover glass is stuck on the surface of the quartzsubstrate, and a gap therebetween is filled with a transparent resinhaving a refractive index different from that of quartz by vacuuminjection, spin coating, or spraying. The resin in the spherical lensplanes formed by wet etching is perfectly cured by UV irradiation orheating, Examples of the resins used herein include an epoxy basedresin, an acrylic based resin, a silicon based resin, and a fluorinebased resin, each of which is curable by UV-irradiation or heating. Inthis way, microlenses arrayed in a pattern corresponding to an arraypattern of pixels are formed. Finally, in a step 1D, the cover glass ispolished, and a transparent electrode made from ITO is formed, to form acounter substrate. While not shown, the counter substrate is stuck on adrive substrate on which pixel electrodes and thin film transistors arepreviously formed, and liquid crystal is injected in a gap therebetween,to obtain an active matrix type liquid crystal display device.

[0009]FIG. 2 shows a schematic configuration of optics (mainly,illumination optics) of a related art projector. The projector includesa light source 1101, a first microlens array 1102, a second microlensarray 1103, a PS synthesizing element 1104, a condenser lens 1105, afield lens 1106, a liquid crystal panel 1107, and a projection lens1108, which are arranged in this order along an optical axis 1100. Themicrolens array 1102 has a plurality of microlenses arrayed in atwo-dimensional pattern, and the microlens array 1103 has a plurality ofmicrolenses arrayed in a two-dimensional pattern. The PS synthesizingelement 1104 includes a plurality of half-wave plates 1104A at positionseach of which corresponds to a space between adjacent two of themicrolenses of the second microlens array 1103.

[0010] In this projector, illumination light emitted from the lightsource 1101 passes through the microlense arrays 1102 and 1103, to bedivided into a plurality of micro-beams. The light emerged from themicrolens arrays 1102 and 1103 is made incident on the PS synthesizingelement 1104. Light L10 incident on the PS synthesizing element 1104contains a P-polarized component and an S-polarized componentperpendicular to each other within a plane perpendicular to the opticalaxis 1100. The PS synthesizing element 1104 separates the light L10incident thereon into two kinds of polarized light components L11 andL12 (P-polarized component and S-polarized component). Of thesepolarized light components L11 and L12, the polarized light componentL11 (for example, P-polarized component) emerges from the PSsynthesizing element 1104 with its polarization direction (for example,P-polarization) kept as it is, and the polarized light component L12(for example, S-polarized component) is converted into the otherpolarized light component (for example, P-polarized component) by thehalf-wave plates 1104A, and the converted light component L12 emergesfrom the PS synthesizing element 1104. As a result, the two separatedpolarized light components L11 and L12 are directed in a specificdirection.

[0011] The light emerged from the PS synthesizing element 1104 passesthrough the condenser lens 1105 and the field lens 1106, and illuminatesthe liquid crystal panel 1107. The micro-beams divided from the light bythe microlens arrays 1102 and 1103 are enlarged at an enlargement ratiodetermined by the focal distance “fc” of the condenser lens 1105 and thefocal distance “f” of the microlenses 1103M of the second microlensarray 1103, to illuminate the entire incident plane of the liquidcrystal panel 1107. Accordingly, a plurality of the enlarged beams aresuperimposed on the incident plane of the liquid crystal panel 1107, torealize uniform illumination as a whole. The liquid crystal panel 1107spatially modulates the incident light on the basis of image signals,and the light emerged from the liquid crystal panel 1107 is projected ona screen (not shown) by the projection lens 1108, to form an image onthe screen.

[0012]FIG. 3 is a typical perspective view showing one example of aliquid crystal panel. A liquid crystal panel (liquid crystal displaydevice) shown in the figure has a flat panel structure including a pairof substrates 1201 and 1202 and liquid crystal 1203 kept therebetween. Apixel array portion 1204 and a drive circuit portion are integrated onthe lower substrate 1201. The drive circuit portion is separated into avertical drive circuit 1205 and a horizontal drive circuit 1206.Terminals 1207 for external connection are formed on a peripheral upperend of the lower substrate 1201. The terminals 1207 are connected to thevertical drive circuit 1205 and the horizontal drive circuit 1206 viawiring lines 1208. Gate lines G and signal lines S are formed on thepixel array portion 1204. A pixel electrode 1209 and a thin filmtransistor (TFT) 1210 for driving the pixel electrode 1209 are formed ateach of intersections between the gate lines G and the signal lines S. Apixel P is composed of a combination of the pixel electrode 1209 and thethin film transistor 1210. A gate electrode of the thin film transistor1210 is connected to the corresponding gate line G, a drain resinthereof is connected to the corresponding pixel electrode 1209, and asource region thereof is connected to the corresponding signal line S.The gate line G is connected to the vertical drive circuit 1205, and thesignal line S is connected to the horizontal drive circuit 1206. Thevertical drive circuit 1205 sequentially selects each pixel P via thegate line G. The horizontal drive circuit 1206 writes an image signal onthe selected pixel P via the signal line S. The lower substrate 1201, onwhich the pixel electrodes and the thin film transistors (TFTs) areintegrated, is called as a TFT substrate. While not shown, a counterelectrode and color filter are formed on the upper substrate 1202, andtherefore, the upper substrate 1202 is called as a counter substrate.

[0013] Such a microlens array must meet the requirement toward higherprecision as well as the requirement toward higher luminance. Forexample, as the panel size of a liquid crystal display device becomessmall, the pixel size becomes small in proportion thereto, andcorrespondingly, a cover glass must be made thin. Although a cover glasshas been thinned by polishing or grinding, such polishing or grindinghas a limitation in thinning the cover glass at a desired accuracy,thereby making it difficult to ensure the uniformity and flatnessrequired for design. If the accuracy and flatness of the plane of acover glass for a microlens array is insufficient, there arises aproblem that mechanical stress may occur at the time of assembling themicrolens array in a liquid crystal display device. Also, in the case ofthinning a cover glass to 30 μm or less along with the requirementtoward higher definition of a panel, there arises another problem thatwaviness or warping of the cover glass may occur by stress due toshrinkage caused by curing of an optical resin forming the microlensarray or a difference in thermal expansion coefficient between theoptical resin and the cover glass.

[0014] In the case of using the above-described active matrix typeliquid crystal display device as a light bulb of a projector, such aliquid crystal display device is more strongly required for higherdefinition and high luminance. From this viewpoint, a high temperaturepolysilicon thin film transistor capable of realizing high definition isused as a switching device for driving each pixel. Along with the demandtoward a finer switching device, a microlens array is required to have afiner structure. To meet such a requirement, a technique of integratinga microlens array to a substrate of an active matrix type liquid crystaldisplay device has been developed. For example, a method of producing amicrolens array incorporating substrate has been disclosed, for example,in Japanese Patent Laid open No. Hei 5-341283, Hei 10-161097, and2000-147500.

[0015] A duel microlens array structure is regarded as an idealstructure capable of realizing the maximum luminance, wherein amicrolens array functioning as condenser lenses is assembled in acounter substrate on the light incident side, and a microlens arrayfunctioning as field lenses is assembled on a TFT substrate side. Such aduel microlens array is able to enhance the effective aperture ratio ofpixels at maximum; however, because of the most difficulty in producingthe duel microlens array, any practical production method thereof hasbeen not disclosed at present. It is to be noted that an LCD having aduel microlens array structure is often called as an MTMLCD abbreviatedfrom “Microlens Substrate-TFT Substrate-Microlens Substrate LCD”.

SUMMARY OF THE INVENTION

[0016] A first object of the present invention is to provide a method ofproducing a microlens array excellent in surface accuracy and a flatnesswhile eliminating the need of provision of a cover glass (glasssubstrate), and to provide a method of producing a so-called duelmicrolens array (sometimes called as a double microlens array) in whichtwo microlens arrays are joined to each other by using a planarizingtechnique.

[0017] A second object of the present invention is to provide a liquidcrystal display device incorporating the above microlens array.

[0018] A third object of the present invention is to provide a projectorusing the above liquid crystal display device.

[0019] A fourth object of the present invention is to provide a methodof rationally producing a liquid crystal display device having a dualmicrolens array.

[0020] To achieve the above first object, according to a first aspect ofthe present invention, there is provided a method of producing amicrolens array, including a patterning step of forming a first opticalresin layer having a first refractive index on a transparent substrateand forming a plurality of microlens planes arrayed in a two-dimensionalpattern on the front surface of the first optical resin layer; aplanarizing step of forming a planarized second optical resin layer; ajoining step of providing a support layer on which a transparentprotective film is previously formed; and a removing step of removingthe support layer in such a manner that only the protective film remainson the second optical resin layer. In this method, the planarizing stepincludes a step of filling irregularities of the microlens planes with aresin having a second refractive index and planarizing the frontsurface, opposed to the microlens planes, of the resin, to form theplanarized second optical resin layer, and the joining step includes astep of joining the support layer to the planarized second optical resinlayer.

[0021] The joining step may be performed before the planarizing step. Inthis case, the joining step may include a step of joining the supportlayer to the microlens side of the first optical resin layer with aspecific gap kept therebetween, and the planarizing step may include astep of filling the gap with a liquid resin and curing the resin, toform the planarized second optical resin layer.

[0022] The planarizing step may include a step of coating the frontsurface of the first optical resin layer with a liquid resin by aspin-coating process so as to fill the microlens planes with the liquidresin and to planarize the front surface of the liquid resin, to formthe polarized second optical resin layer.

[0023] The planarizing step may include a step of supplying a resin onthe front surface side of the first optical resin layer to fill themicrolens planes with the resin, and pressing the front surface, opposedto the microlens planes, of the resin with a stamper having a flatplane, to form the planarized second optical resin layer.

[0024] The protective film is preferably made from SiO₂, SiN, a-DLN, orAl₂O₃.

[0025] To achieve the above first object, according to a second aspectof the present invention, there is provided a method of producing amicrolens array, including a patterning step of forming a first opticalresin layer having a first refractive index on a transparent substrateand forming a plurality of microlens planes arrayed in a two-dimensionalpattern on the front surface of the first optical resin layer; and afilling/plarizing step of filling irregularities of the microlens planeswith a resin having a second refractive index, and planarizing the frontsurface, opposed to the microlens planes, of the resin, to form a secondoptical resin layer. In this method, the filling/planarizing step isperformed by a spin-coating process.

[0026] To achieve the above first object, according to a third aspect ofthe present invention, there is provided a method of producing amicrolens array, including a patterning step of forming a first opticalresin layer having a first refractive index on a transparent substrateand forming a plurality of microlens planes arrayed in a two-dimensionalpattern on the front surface of the first optical resin layer; a fillingstep of filling irregularities of the microlens planes with a resinhaving a second refractive index; and a planarizing step of planarizingthe front surface, opposed to the microlens planes, of the resin fillingthe microlens planes, to form a second optical resin layer. In thismethod, the planarizing step is performed by planarizing the frontsurface of the resin filling the microlens planes by a flat stampingprocess.

[0027] To achieve the above first object, according to a fourth aspectof the present invention, there is provided a method of producing amicrolens array having a double structure, including a first patterningstep of forming a first optical resin layer on a first support andforming two-dimensionally arrayed first microlens planes on the frontsurface of the first optical resin layer; a first planarizing step offilling irregularities of the first microlens planes with an opticalresin having a refractive index different from that of the first opticalresin layer, and planarizing the front surface, opposed to the microlensplanes, of the optical resin, to form a first microlens array; a secondpatterning step of forming a second optical resin layer on a secondsupport and forming two-dimensionally arrayed second microlens planes onthe front surface of the second optical resin layer; a secondplanarizing step of filling irregularities of the second microlensplanes with an optical resin having a refractive index different fromthat of the second optical resin layer, to form a second microlensarray; and a joining step of joining the planarized surface of the firstmicrolens array to the planarized surface of the second microlens arrayin a state that the first microlens planes are aligned to the secondmicrolens planes, thereby integrating the first and second microlensarrays to each other.

[0028] To achieve the above second aspect, according to a fifth aspectof the present invention, there is provided a liquid crystal displaydevice having a panel structure including a drive substrate on which atleast pixel electrodes and switching devices for driving the pixelelectrodes are formed; a counter substrate on which at least a counterelectrode is formed; and a liquid crystal layer interposed between thedrive substrate and the counter substrate joined such that the pixelelectrodes are opposed to the counter electrode with a specific gap kepttherebetween. In this device, a microlens array composed of microlensarrayed in a two-dimensional pattern corresponding to an array patternof the pixel electrodes is assembled at least to the counter substrate.The microlens array has the back surface joined to the counter substrateand the front surface planarized, and the counter electrode is formed onthe planarized front surface of the microlens array via a protectivefilm.

[0029] Preferably, after the protective film previously formed on asupport is bonded on the planarized front surface of the microlensarray, the support is removed to expose the protective film, and thecounter electrode is formed on the exposed protective film.

[0030] The protective film is preferably made from Al₂O₃, a-DLC, TiO₂,TiN, or Si.

[0031] Preferably, the microlens array has a double structure includingfirst microlenses functioning as condenser lenses disposed on the sideapart from the liquid crystal layer and second microlenses substantiallyfunctioning as field lenses disposed on the side close to the liquidcrystal layer, and the distance between a principal point of each of thesecond microlenses and the liquid crystal layer is set to a value in arange of 10 μm or less.

[0032] It is to be noted that if the focal distance of the secondmicrolens corresponds to the distance between both the first and secondmicrolenses, the function of the second microlens becomes 100%, and inactual, if the difference between the focal distance of the secondmicrolens and the distance between both the first and second microlensesis within about 10%, the second microlens sufficiently functions as afield lens.

[0033] To achieve the above second object, according to a sixth aspectof the present invention, there is provided a liquid crystal displaydevice having a panel structure including a drive substrate on which atleast pixel electrodes and switching devices for driving the pixelelectrodes are formed; a counter substrate on which at least a counterelectrode is formed; and a liquid crystal layer interposed between thedrive substrate and the counter substrate joined such that the pixelelectrodes are opposed to the counter electrode with a specific gap kepttherebetween; wherein a microlens array composed of microlens arrayed ina two-dimensional pattern corresponding to an array pattern of the pixelelectrodes is assembled at least to the drive substrate. In this device,the microlens array has a stacked structure of a first optical resinlayer having a first refractive index and a second optical resin layerhaving a second refractive index. The first optical resin layer hasmicrolens planes arrayed in a two-dimensional pattern and the secondoptical resin layer is formed to fill irregularities of the microlensplanes and has a planarized front surface opposed to the microlensplanes. The microlens array is assembled to the drive substrate in sucha manner that the planarized surface of the second optical resin layerof the microlens array is joined to the back surface of the drivesubstrate preferably, the microlens array is formed by joining the firstoptical resin layer to a support layer having a protective filmpreviously formed thereon with a specific gap kept therebetween, fillingthe gap with a liquid resin and curing the liquid resin to form thesecond optical resin layer, and removing the support layer to expose theprotective film. The exposed surface of the protective film is taken asthe planarized surface of the second optical resin layer.

[0034] Preferably, the microlens array is formed by filling themicrolens planes of the first optical resin layer with a resin, andpressing the front surface, opposed to the microlens planes, of theresin with a stamper having a flat plane, to planarize the front surfaceof the second optical resin layer.

[0035] The liquid crystal display device preferably further includes amicrolens array disposed on the counter substrate in such a manner as tobe aligned to the microlens array disposed on the drive substrate,wherein one of the microlens arrays functions as condenser lenses andthe other functions as field lenses.

[0036] Preferably, the drive substrate is thinned by polishing the backsurface thereof, and the planarized surface of the second optical resinlayer of the microlens array is joined to the polished back surface ofthe drive substrate.

[0037] To achieve the above third object, according to a seventh aspectof the present invention, there is provided a projector including alight source for emitting light; a liquid crystal display device havinga function of optically modulating incident light; and a projection lensfor projecting light modulated by the liquid crystal display device. Theliquid crystal display device having a panel structure includes a drivesubstrate on which at least pixel electrodes and switching devices fordriving the pixel electrodes are formed; a counter substrate on which atleast a counter electrode is formed; and a liquid crystal layerinterposed between the drive substrate and the counter substrate joinedsuch that the pixel electrodes are opposed to the counter electrode witha specific gap kept therebetween. In this device, a microlens arraycomposed of microlens arrayed in a two-dimensional pattern correspondingto an array pattern of the pixel electrodes is assembled at least to thecounter substrate. The microlens array has the back surface joined tothe counter substrate and the front surface planarized, and the counterelectrode is formed on the planarized front surface of the microlensarray via a protective film.

[0038] To achieve the third aspect, according to an eighth aspect of thepresent invention, there is provided a projector including a lightsource for emitting light; a liquid crystal display device having afunction of optically modulating incident light; and a projection lensfor projecting light modulated by the liquid crystal display device. Theliquid crystal display device having a panel structure includes a drivesubstrate on which at least pixel electrodes and switching devices fordriving the pixel electrodes are formed; a counter substrate on which atleast a counter electrode is formed; and a liquid crystal layerinterposed between the drive substrate and the counter substrate joinedsuch that the pixel electrodes are opposed to the counter electrode witha specific gap kept therebetween. In the device, a microlens arraycomposed of microlens arrayed in a two-dimensional pattern correspondingto an array pattern of the pixel electrodes is assembled at least to thedrive substrate. The microlens array has a stacked structure of a firstoptical resin layer having a first refractive index and a second opticalresin layer having a second refractive index. The first optical resinlayer has microlens planes arrayed in a two-dimensional pattern, and thesecond optical resin layer is formed to fill irregularities of themicrolens planes and has a planarized front surface opposed to themicrolens planes. The microlens array is assembled to the drivesubstrate in such a manner that the planarized surface of the secondoptical resin layer of the microlens array is joined to the back surfaceof the drive substrate.

[0039] To achieve the above object, according to a ninth aspect of thepresent invention, there is provided a method of producing a liquidcrystal display device having a panel structure including a firstsubstrate having the front surface on which at least pixel electrodesand switching devices for driving the pixel electrodes are formed andthe back surface opposed to the front surface; a second substrate havingthe front surface on which at least a counter electrode is formed andthe back surface opposed to the front surface; and a liquid crystallayer interposed between the first and second substrates joined suchthat the pixel electrodes are opposed to the counter electrode with aspecific gap kept therebetween. A first microlens array composed oftwo-dimensionally arrayed microlenses for individually condensing lightto the pixel electrodes is integrally formed on one of the first andsecond substrates. A second microlens array composed oftwo-dimensionally arrayed microlenses for allowing light individuallycondensed to the pixel electrodes to pass therethrough is integrallyformed on the other of the first and second substrates. The methodincludes a bonding step of bonding a base plate to the front surface ofeach of the first and second substrates; a polishing step of polishingthe back surface of the substrate in a state that the substrate is heldby the base plate, to reduce the thickness of the substrate; a stickingstep of sticking the corresponding one of the first and second microlensarrays to the polished back surface of the substrate via a transparentoptical resin having a refractive index higher or lower than that of thesubstrate; and a peeling step of peeling the base plate from the frontsurface of the substrate and cleaning the substrate, thereby integratingthe corresponding microlens array to the back surface of the substrate.

[0040] The method may further includes a dividing step of dividing, ifat least one of the first and second substrates is a multi-chip modulesubstrate having an area corresponding to a plurality of panels, themulti-chip module into single substrates corresponding to individualpanels. In this case, after a plurality of the corresponding ones of thefirst and second microlens arrays, which correspond to the plurality ofpanels, are integrated to the multi-chip module substrate by the bondingstep, polishing step, sticking step, and peeling step, the multi-chipmodule substrate may be divided into single substrates corresponding toindividual panels at a suitable stage.

[0041] In the case where one of the first and second substrates is amulti-chip module substrate having an area corresponding to a pluralityof panels and the other is a single-chip module substrate, preferably, aplurality of the corresponding ones of the first and second microlensarrays, which correspond to the plurality of panels, are formed on themulti-chip module substrate; the multi-chip module substrate isimmediately divided into single substrates corresponding to individualpanels in the dividing step; the single-chip module substrates to eachof which the corresponding one of the first and second microlens arraysis previously integrated are prepared; and the single substrates dividedfrom the multi-chip module substrate are overlapped to the single-chipmodule substrates in one-to-one relationship with a specific gap kepttherebetween, to be assembled into individual panels.

[0042] In the case where one of the first and second substrates is amulti-chip module substrate having an area corresponding to a pluralityof panels and the other is a single-chip module substrate, preferably, aplurality of the corresponding ones of the first and second microlensarrays, which correspond to the plurality of panels, are formed on-themulti-chip module substrate; the single-chip module substrates to eachof which the corresponding one of the first and second microlens arraysis previously integrated are prepared; the single-chip module substratesare assembled to the multi-chip module substrate; and the multi-chipmodule substrate assembled with the single-chip module substrates isdivided into individual panels in the dividing step.

[0043] In the case where one of the first and second substrates is amulti-chip module substrate to which a plurality of the correspondingones of the first and second microlens arrays for a plurality of panelsare integrated, and the other of the first and second substrates is alsoa multi-chip module substrate to which a plurality of the others of thefirst and second microlens arrays for a plurality of panels areintegrated, preferably, the multi-chip module substrates are overlappedto each other with a specific gap kept therebetween, to be assembledinto a panel base corresponding to the plurality of panels; and thepanel base is divided into individual panels in the dividing step.

[0044] The dividing step may include a first dicing step of partiallycutting the multi-chip module substrate along boundaries defined topartition the multi-chip module substrate into individual panels byfirst dicing, to form grooves having V-shapes in cross-section; and asecond dicing step of perfectly cutting the grooves by second dicing,thereby forming single substrates with chamfered end faces.

[0045] The method may include an alignment step of forming, afterpeeling the base plate from the front surface of the substrate andcleaning the substrate in the peeling step, an alignment layer foraligning the liquid crystal layer on the exposed front surface of thesubstrate in such a temperature range as not to impair the heatresistance of the microlens array integrated to the substrate.

[0046] The method may include an alignment step of forming an alignmentlayer for aligning the liquid crystal layer on the front surface of thesubstrate; wherein the alignment step is performed before the microlensarray is integrated to the back surface of the substrate by the bondingstep, polishing step, sticking step, and peeling step.

[0047] The polishing step may be performed by one or a combination oftwo or more of buffing with a grade suitable for optics, particleblasting, chemical-mechanical polishing, and chemical etching.

[0048] In the polishing step, preferably, the thickness of the substrateis reduced by polishing the back surface of the substrate in such amanner that the focal point of each of microlenses of the secondmicrolens array functioning as field lenses corresponds to a principalpoint of each of microlens of the first microlens array functioning ascondenser lenses at the time of assembling the first and secondsubstrates into a panel.

[0049] The sticking step may include a step of preparing the microlensarray composed of microlens planes arrayed in a two-dimensional patternby processing an optical glass material having a relatively lowrefractive index; and a step of positioning the microlens array to thepolished back surface of the substrate, overlapping the microlens arraythereto with a specific gap kept therebetween, filling the gap with atransparent optical resin having a refractive index higher or lower thanthat of the substrate, and curing the transparent optical resin.

[0050] The sticking step may include a step of fixing the polished backsurface of the substrate to the microlens array with a specific gap kepttherebetween by a seal material, filling the gap with a transparentoptical resin having a refractive index higher or lower than that of thesubstrate, and sealing the gap.

[0051] The microlens planes are preferably formed into spheric,aspheric, or Fresnel shapes.

[0052] The method may further includes a cleaning step of cleaning thebase plate peeled as a spent product in the peeling step in order tore-use the base plate.

[0053] The method may further include a preliminary step of integratingthe corresponding one of the first and second microlens arrays to thesecond substrate; and an assembling step of assembling the secondsubstrate integrated with the microlens array to the front surface ofthe first substrate. In this case, the bonding step may include a stepof bonding the base plate to the front surface side of the secondsubstrate assembled on the front surface of the first substrate; thepolishing step may include a step of polishing the back surface of thefirst substrate in a state that the panel is held by the base plate; andthe sticking step may include a step of sticking the corresponding oneof the first and second microlens arrays to the polished back surface ofthe first substrate.

[0054] The polishing step may include a step of polishing the backsurface of the first substrate in a state that a plurality of terminalsfor external connection formed on the first substrate are kept at thesame potential.

[0055] The bonding step may include a step of mounting the secondsubstrate side of the panel to the base plate fixed to a polishingplaten used for the polishing step.

[0056] According to the present invention, since the surface of amicrolens array is planarized by etching, flat stamping, orspin-coating, it is possible to eliminate the need of provision of aglass substrate (cover glass). This is advantageous in thinning themicrolens array, and in removing mechanical stress at the time ofassembling the microlens array to a liquid crystal display device.Further, since two microlens arrays can be accurately joined to eachother by making use of a planarizing technique such as etching, flatstamping, or spin-coating, it is possible to stably produce a so-calleddual microlens array.

[0057] According to the present invention, a microlens arrayincorporating TFT substrate is prepared by sticking a base plate on thefront surface of a TFT substrate with an adhesive, polishing the backsurface of the TFT substrate by a method for one-surface polishing witha grade suitable for optics, to form a TFT thin substrate having aspecific thickness, and sticking a microlens array on the TFT thinsubstrate with a transparent resin adhesive having a high refractiveindex. A microlens array incorporating counter substrate is alsoprepared by a process similar to that described above. These substratesare overlapped to each other with a specific gap kept therebetween, andliquid crystal is enclosed in a gap therebetween and is sealed, toproduce a liquid crystal display device having a duel microlens arraystructure. Such a dual microlens type liquid crystal display device issuitable, for example, for a light bulb of a projector. Since themicrolens array functioning as condenser lenses for a liquid crystallayer and the other microlens array functioning as field lenses can bedisposed in close-proximity to each other, it is possible to obtain anoptimal function of the microlenses, and hence to significantly improvethe effective aperture ratio of pixels.

BRIEF DESCRIPTION OF THE DRAWINGS

[0058] These and other objects, features, and advantages of the presentinvention will be more apparent from the following description inconjunction with the accompanying drawings, wherein:

[0059]FIGS. 1A to 1D are process diagrams showing a related art methodof producing a liquid crystal display device;

[0060]FIG. 2 is a typical diagram showing one example of a related artprojector;

[0061]FIG. 3 is a typical perspective view showing one example of aliquid crystal display device to be assembled in the projector shown inPIG. 39;

[0062]FIGS. 4A to 4D are process diagrams showing a method of producinga microlens array according to the present invention;

[0063]FIGS. 5A to 5C′ are process diagrams showing another method ofproducing a microlens array according to the present invention;

[0064]FIGS. 6A to 6D are process diagrams showing essential steps of afurther method of producing a microlens array according to the presentinvention;

[0065]FIG. 7 is a typical sectional view showing a reference example ofa duel microlens array;

[0066]FIG. 8 is a graph showing optical characteristic of the microlensarray shown in FIG. 7;

[0067]FIGS. 9A to 9E are process diagrams for illustrating a liquidcrystal display device according to the present invention;

[0068]FIGS. 10A to 10E are process diagrams for illustrating anotherliquid crystal display device according to the present invention;

[0069]FIGS. 11A to 11E are process diagrams for illustrating a furtherliquid crystal display device according to the present invention;

[0070]FIG. 12 is a typical partial sectional view showing a referenceexample of a general liquid crystal display device;

[0071]FIGS. 13A to 13F are process diagrams for illustrating a furtherliquid crystal display device according to the present invention;

[0072]FIGS. 14A and 14B are enlarged views of the liquid crystal displaydevice shown in FIGS. 13A to 13;

[0073]FIGS. 15A to 15F are process diagrams for illustrating a furtherliquid crystal display device according to the present invention;

[0074]FIG. 16 is a typical diagram showing optical characteristics of aliquid crystal display device according to the present invention;

[0075]FIG. 17 is a perspective view showing the entire configuration ofa liquid crystal display device according to the present invention;

[0076]FIG. 18 is a typical diagram showing one example of a projectoraccording to the present invention;

[0077]FIGS. 19A to 19E are process diagrams showing a method of a liquidcrystal display device according to the present invention;

[0078]FIG. 20 is a process diagram showing an embodiment of the methodof producing a liquid crystal display device according to the presentinvention;

[0079]FIGS. 21A and 21B are typical diagrams showing a dividing step ofthe production method;

[0080]FIG. 22 is a process diagram showing another embodiment of themethod of producing a liquid crystal display device according to thepresent invention;

[0081]FIG. 23 is a typical diagram showing an assembling step of theproduction method;

[0082]FIGS. 24A and 24B are typical diagrams showing a method ofproducing a microlens array incorporating counter substrate;

[0083]FIG. 25 is a process diagram showing a further embodiment of themethod of producing a liquid crystal display device according to thepresent invention;

[0084]FIG. 26 is a process diagram showing a further embodiment of themethod of producing a liquid crystal display device according to thepresent invention;

[0085]FIG. 27 is a process diagram showing a further embodiment of themethod of producing a liquid crystal display device according to thepresent invention;

[0086]FIG. 28 is a process diagram showing a further embodiment of themethod of producing a liquid crystal display device according to thepresent invention;

[0087]FIG. 29 is a process diagram showing a further embodiment of themethod of producing a liquid crystal display device according to thepresent invention;

[0088]FIG. 30 is a process diagram showing a further embodiment of themethod of producing a liquid crystal display device according to thepresent invention;

[0089]FIG. 31 is a typical diagram showing a further embodiment of themethod of producing a liquid crystal display device according to thepresent invention;

[0090]FIG. 32 is a typical diagram showing a panel taking a measureagainst static electricity;

[0091]FIG. 33 is a typical diagram showing another panel taking ameasure against static electricity;

[0092]FIG. 34 is a typical diagram showing a polishing step;

[0093]FIG. 35 is a typical diagram showing another polishing step;

[0094]FIG. 36 is a sectional view showing a sticking step using anoptical resin;

[0095]FIG. 37 is a plane view of FIG. 36, showing the sticking stepusing an optical resin;

[0096]FIGS. 38A to 38C are typical sectional views showing anotherpolishing step;

[0097]FIG. 39 is a sectional view showing one example of the liquidcrystal display device produced according to the present invention; and

[0098]FIG. 40 is a typical diagram showing one example of the liquidcrystal display device produced according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0099] Hereinafter, a method of producing a microlens array, a liquidcrystal display device using the microlens array, a projector using theliquid crystal display device, and a method of producing a liquidcrystal display device according to the present invention will bedescribed in this order with reference to the drawings, in whichpreferred embodiments are shown.

[0100] 1. Method of Producing Microlens Array

[0101] A first embodiment of a method of producing a microlens arrayaccording to the present invention will be described with reference toFIGS. 4A to 4D.

[0102] In a patterning step shown in FIG. 4A, a first optical resinlayer 2 having a first refractive index is formed on a substrate 1 madefrom a transparent glass or the like, and a plurality of microlensplanes arranged in a two-dimensional pattern are formed on the surfaceof the first optical resin layer 2. In this embodiment, the firstoptical resin layer 2 made from a UV-cured type resin having a lowrefractive index is previously formed on the glass substrate 1, and anNi-electroformed original having a plurality of microlens planes isstamped on the surface of the first optical resin layer 2, to transferthe microlens planes to the surface of the first optical resin layer 2,The first optical resin layer 2 made from the UV-cured type resin iscured by irradiating the first optical resin layer 2 with ultravioletrays from the back side of the glass substrate 1, to fix the microlensplanes transferred to the first optical resin layer 2.

[0103] In a joining step shown in FIG. 4B, a support layer 4 on which atransparent protective film 3 is previously formed is joined to theglass substrate 1 side by a seal material 5. The support layer 4 is madefrom a cover glass. The protective film 3 previously formed on onesurface of the support layer 4 functions as a polishing stopper at thetime of polishing the support layer 4 made from the cover glass in thesubsequent step. The protective film 3 may be made from an insulatingmaterial such as SiO₂, SiN, a-DLC (amorphous diamond-like carbon), orAl₂O₃. The seal material 5 for joining the support layer 4 to the glasssubstrate 1 side is composed of a resin applied along the outerperipheral portion of the support layer 4, and contains glass fibershaving diameters ranging from 2 to 3 μm as a spacer. The support layer4, the outer peripheral portion of which is coated with the sealer 5, isbonded on the glass substrate 1 side, to form an internal spacetherebetween.

[0104] In a filling/planarizing step shown in FIG. 4C, the internalspace surrounded by the first optical resin layer 2 and the protectivefilm 3 is filled with a liquid resin having a second refractive index,and the liquid resin is cured, to form a microlens array between thefirst optical resin layer 2 and the protective film 3. In thisembodiment, a resin having a high refractive index is injected under avacuum in the internal space between the first optical resin layer 2 andthe protective film 3, and is cured by heating. Alternatively, aUV-cured type resin may be injected in the internal space and cured byUV irradiation. In this way, irregularities of the microlens planesformed on the surface of the first optical resin layer 2 are filled withthe liquid resin having the second refractive index, and simultaneouslythe surface, opposed to the microlens planes, of the resin isplanarized. The resin is then cured, to form a second optical resinlayer 6. The microlens array is thus formed by stacking the firstoptical resin layer 2 and the second optical resin layer 6 different inrefractive index to each other. In this embodiment, since the liquidresin for forming the second optical resin layer 6 is injected in thegap between the glass substrate 1 and the support layer 4, the surface,opposed to the microlens array, of the second optical resin layer 6 isautomatically planarized.

[0105] In a removing step shown in FIG. 4D, the support layer 4 madefrom the cover glass is removed by polishing or grinding with theprotective film 3 used as a stopper until only the protective film 3remains on the second optical resin layer 6.

[0106] With the series of these steps, a microlens array with no coverglass can be produced.

[0107] According to this embodiment, the joining step is performedbefore the filling/planarizing step in order to form a gap required forthe next filling/planarizing step. To be more specific, the supportlayer 4 is joined to the first optical resin layer 2 with a specific gapkept therebetween, and the liquid resin is injected in the gap and thencured. In this step, the surface, opposed to the microlens planes, ofthe resin is simultaneously planarized.

[0108] The method of producing a microlens array according to thepresent invention is not limited to this embodiment but may include apatterning step of forming a first optical resin layer having a firstrefractive index on a transparent substrate and forming a plurality ofmicrolens planes arranged in a two-dimensional pattern on the surface ofthe first optical resin layer, a filling/planarizing step of filling theirregularities of the microlens planes with a resin having a secondrefractive index and planarizing the surface, opposed to the microlensplanes, of the resin, to form a second optical resin layer, a joiningstep of joining a support layer, on which a transparent protective filmis previously formed, to the planarized second optical resin layer, anda removing step of removing the support layer until only the protectivefilm remains on the second optical resin layer.

[0109] A second embodiment of the method of producing a microlens arrayaccording to the present invention will be described with reference toFIGS. 5A to 5C′. In this embodiment, the surface, opposed to a microlensarray, of a resin is planarized by a stamping method.

[0110] In a patterning step shown in FIG. 5A, a first optical resinlayer 2 having a first refractive index is formed on the surface of aglass substrate 1, and an Ni-electroformed original having a pluralityof microlens planes is stamped to the surface of the first optical resinlayer 2, to transfer the microlens planes to the surface of the firstoptical resin layer 2. Like the first embodiment, the first opticalresin layer 2 is made from a UV-cured type resin having a low refractiveindex, The first optical resin layer 2 is irradiated with ultravioletrays (wavelength: near 365 nm) at an energy of 3,000 mJ from the backside of the glass substrate 1, to cure the UV-cured type resin, therebyfixing the microlens planes transferred to the first optical resin layer2.

[0111] In a filling/planarizing step shown in FIG. 5B, theirregularities of the microlens planes are filled with a resin having asecond refractive index, and the surface, opposed to the microlensplanes, of the resin is planarized by a flat stamper FS, to form asecond optical resin layer 6. In this embodiment, a UV-cured type resinhaving a high refractive index is dropped in the irregularities of themicrolens planes, and the surface, opposed to the microlens planes, ofthe resin is planarized by the flat stamper FS. In such a state, thesecond optical resin layer 6 is cured by UV irradiation, to fix theplanarized surface of the second optical layer 6. In addition, theliquid resin may be supplied to the irregularities of the microlensplanes by spin-coating in place of dropping.

[0112] In a film formation step shown in FIG. 5C, a protective film 3made from SiO₂ or SiN is formed on the surface of the planarized secondoptical resin layer 6 by CVD (Chemical Vapor Deposition) or sputtering,and then a transparent electrode 7 made from ITO (Indium Tin Oxide) isformed on the surface of the protective film 3.

[0113] A step shown in FIG. 5C′ may be performed in place of the stepshown in FIG. 5C. In this step, a thin cover glass layer 4 is bonded onthe planarized second optical resin layer 3, and the transparentelectrode 7 is formed on the cover glass layer 4. In this way, in thestep shown in FIG. 5C′, the cover glass layer 4 is used in place of theprotective film 3 used in the step shown in FIG. 5C. If needed, thecover glass layer 4 may be thinned by polishing or grinding.

[0114] According to this embodiment, a substrate for a liquid crystaldisplay, which includes a microlens array integrated with thetransparent electrode, can be thus produced. Such a substrate isadvantageous in that since the surface of the microlens array isplanarized, the substrate does not cause any unnecessary stress whenbeing assembled in a liquid crystal display device. In particular, byadopting the step shown in FIG. 5C, the microlens array without coverglass can be produced. This is advantageous in reducing the productioncost.

[0115] A third embodiment of the method of producing a microlens arraywill be described with reference to FIGS. 6A to 6D. In this embodiment,the surface, opposed to a microlens array, of a resin is planarized by aspin-coating method.

[0116] In a first spin coating step shown in FIG. 6A, after a firstoptical resin layer 2 having a first refractive index is formed on atransparent glass substrate 1 and a plurality of microlens planes(depth: about 7 μm) arranged in a two-dimensional pattern are formed onthe surface of the first optical resin layer 2, first spin coating isperformed. In this first spin coating, the microlens planes are coatedwith a liquid resin having a viscosity of about 100 cps at a rotatingspeed ranging from 500 to 1,000 rpm. As a result, a second optical resinlayer 6 is formed on the bottoms of the microlens planes.

[0117] In a second spin coating step shown in FIG. 6B, second spincoating is performed by re-coating the recessed microlens planes with aliquid resin having a viscosity of about 100 cps at a rotating speedranging from 500 to 1,000 rpm.

[0118] In a third spin coating step shown in FIG. 6C, third spin coatingis performed by re-coating the recessed microlens planes with a liquidresin having a viscosity of 100 cps by a centrifugal force generated byrotation at a rotating speed ranging from 500 to 1,000 rpm. As a resultof repeating the spin coating by three times, the recessed microlensplanes are nearly filled with the second optical resin layer 6.

[0119] Finally, in a fourth spin coating step shown in FIG. 6D, fourthspin coating is performed so as to perfectly fill the microlens planeswith a resin and planarize the surface, opposed to the microlens planes,of the resin. In this step, the rotating speed of a spin coater is setto a high value in a range of 3,000 to 5,000 rpm for smoothening thesurface, opposed to the microlens planes, of the resin.

[0120] The spin coating method may be replaced by a spraying method. Inthis spraying method, the viscosity of a liquid resin is set to aseveral ten cps by using a solvent, and the liquid resin is sprayedwhile being atomized into particles having sizes of several ten Am, andthen dried. The spraying may be performed such that the particles of theliquid resin be flattened by surface tensions thereof, Such spraying anddrying of the resin are repeated. If any solvent is not used, a resinhaving a low viscosity may be used.

[0121] In addition to the above-described simple microlens array, a duelmicrolens array formed by stacking a microlens array functioning as acondenser lens to a microlens array functioning as a field lens has beendeveloped. As compared with a single microlens array, a duel microlensarray is advantageous in improving a utilization efficiency of light.

[0122] In a general three-panel type liquid crystal projector, thedivergence angle of light emitted from a light source and made incidenton a microlens array is often set to about 10°. In the case of using amicrolens array, since the divergence angle of light on the emergenceside of a liquid crystal panel becomes large, even if the divergenceangle of incident angle is made excessively large, the light is kickedby a projection lens, to rather reduce the utilization efficiency oflight. Also, from the viewpoint of preventing a reduction in contrastalong with an increase in divergence angle of light made incident on aliquid crystal panel, the incident angle is restricted to some extent.

[0123] On the contrary, in the case of a duel microlens array structure,since a second lens (field lens) is disposed so as to be apart from afirst lens (condenser lens) by a focal distance of the second lens inthe direction of incident light, the divergence angle of light emergingfrom a (field lens arranged type) panel is controlled by the divergenceangle due to a lens power of the duel microlens array, to reduce thedegree of kicking of light by a projection lens, thereby raising theutilization efficiency of light.

[0124] Dual microlens arrays (DMLs) have two kinds of arrangementstructures for the liquid crystal panels. In general, an active matrixtype liquid crystal panel has a stacked structure formed by joining adrive substrate provided with switching devices such as thin filmtransistors, pixel electrodes, and the like to a counter substrateprovided with a counter electrode and holding liquid crystal between thedrive substrate and the counter substrate. The first kind of the DMLarrangement structure is characterized in that a DML is disposed on thecounter substrate side. The second kind of the DML arrangement structureis characterized in that one microlens array of a DML is disposed on thecounter substrate side and the other microlens array of the DML isdisposed on the drive substrate side, wherein liquid crystal is heldtherebetween.

[0125] Such a DML must cope with the tendency toward high definition ofpixels. To reduce panel sizes, pixel sizes must be reduced in proportionto the reduced panel sizes, and correspondingly, an arrangement pitch ofindividual microlenses must be reduced. As a result, it is required toshorten the focal distances of microlenses and also to thin a coverglass. Of these requirements, the shortening of the focal distances ofmicrolenses can be relatively easily realized; however, the thinning ofa cover glass is more difficult than that in the case of a singlemicrolens array.

[0126] The DML structure is generally produced by sticking two pieces ofsingle microlens arrays (SMLs) to each other. In this case, to meet therequirement toward high definition, the thickness and the like of eachof a cover glass and an optical resin layer in each SML must be morestrictly controlled than those in an ordinary SML.

[0127] A basic configuration of a liquid crystal display device (liquidcrystal panel) in which a DML is formed on the counter substrate sideand a problem thereof to be solved will be described with reference toFIG. 7. As shown in the figure, a liquid crystal display device has astacked structure formed by joining a drive substrate 10 to a countersubstrate 20 by a seal material 31, and enclosing liquid crystal in agap between both the substrates 10 and 20. The drive substrate 10 isformed of a glass base 11, on the surface of which switching devicessuch as thin film transistors and pixels 12 including pixel electrodesare integrated in a matrix pattern. The pixels 12 are partitioned fromeach other by a lattice-shaped black matrix 13.

[0128] A dual microlens array DML and a counter electrode (not shown)are formed on the counter substrate 20. The DML is held between a glasssubstrate 21 and a cover glass 22, and has a stacked structure formed bystacking a low refractive index resin layer 23, a high refractive indexresin layer 24, and a low refractive index resin layer 25 to each other.The low refractive index resin layers 23 and 25 are each made from afluorine-based resin, a silicon-based resin, or an acrylic-based resin,and the high refractive index resin layer 24 is made from anacrylic-based resin, an epoxy-based resin, or a thiourethane-basedresin. A first ML (condenser lens) is formed at the interface betweenthe low refractive index resin layer 23 and the high refractive indexresin layer 24, and a second ML (field lens) is formed at the interfacebetween the high refractive index resin layer 24 and the low refractiveindex resin layer 25.

[0129] As the pixel pitch becomes narrow along with the tendency towardhigh definition of pixels, it becomes important to improve control andaccuracy of a distance {circle over (1)} between the principal point ofthe second ML and the surface of the cover glass 22, a distance {circleover (2)} between the principal point of the first ML and the principalpoint of the second ML, and an alignment value {circle over (3)} betweenthe first ML and the second ML. These parameters {circle over (1)},{circle over (2)}, and {circle over (3)} determine the light collectionratio of the DML. Of these parameters, the distance {circle over (2)}between the principal point of the first ML and the principal point ofthe second ML is required to be strictly controlled for realizing thefunction of the field type DML.

[0130]FIG. 8 is a graph showing a dependency of a light collection ratioon the parameter {circle over (1)} (distance between the principal pointof the second ML and the surface of the cover glass). It is to be notedthat the light collection ratio is expressed in effective aperture ratioof pixels. As is apparent from the graph, to obtain a very high value ofthe light collection ratio, it is preferred to set the parameter {circleover (1)} in a range of about 5 μm or less, and to keep a relativelyhigh value of the light collection ratio, it is preferred to set theparameter {circle over (1)} in a range of 10 μm or less. Accordingly, itis required to make the thickness of the cover glass 22 of the second MLvery thin. The graph of FIG. 8 shows two curves different in parameters.Even on the basis of either of these curves, it is apparent that theparameter {circle over (1)}0 should be suppressed in the range of 10 μmor less. It is to be noted that the graph of FIG. 8 is obtained byplotting data measured under a condition that the pixel pitch is set to18 μm×18 μm and the divergence angle of light emitted from a lightsource and made incident on the panel is set to 10°.

[0131] 2. Liquid Crystal Display Device

[0132] A first embodiment of a liquid crystal display device accordingto the present invention will be described with reference to FIGS. 9A to9E.

[0133]FIGS. 9A to 9E are typical process diagrams showing steps offorming a liquid crystal display device in this embodiment.

[0134] This embodiment is characterized in that a dual microlens arrayis formed on the counter substrate side.

[0135]FIG. 9A shows the step of preparing a first ML substrate and asecond ML substrate. A resin layer 23 having a low refractive index, onthe surface of which microlens planes are previously formed by astamping method, is formed on a first ML substrate 21. A protective film26 is formed as a polishing stopper on a second ML substrate 22, and aresin layer 25 having a low refractive index, on the surface of whichmicrolens planes are previously formed by a stamping method, is formedon the protective film 26. The protective film 26 is made from Al₂O₃ ora-DLC. At the time of polishing the second ML substrate 22 in thesubsequent step, the protective film 26 functions as a stopper capableof ensuring the uniformity of polishing. The film made from Al₂O₃ ora-DLC is transparent, and may have a thickness of about 100 nm or moreto function as an effective stopper. The protective film 26 can beformed by a sputtering process or a PECVD (Plasma Enhanced ChemicalVapor Deposition) process, The stopper film is not necessarilytransparent. For example, the stopper film may be formed by depositinga-Si or the like to a thickness of about 1 μm. The microlens planesformed on each of the low refractive index resin layers 23 and 25 haveaspheric shapes (ellipsoids or hyperboloids) having a curvature radiusand an aspheric constant specified so as to be matched with a pixelpitch and thereby to obtain the maximum light correction efficiency.

[0136]FIG. 9B shows the step of joining the first ML substrate and thesecond ML substrate to each other. An outer peripheral portion of one ofthe first ML substrate. 21 and the second ML substrate 22 is coated witha seal material 27 composed of an epoxy resin or acrylic resin. Afteralignment marks of the first ML substrate 21 and the second ML substrate22 are aligned with each other, the first ML substrate 21 and the secondML substrate 22 are overlapped to each other. The epoxy resin or acrylicresin used for the seal material 27 is of a UV-cured type or aUV-cured/thermally-cured combination type. The resin used as the sealmaterial 27 previously contains glass fibers or plastic beads as aspacer in an amount of 1 to 5 wt % in order to make the distance betweenthe principal point of the first ML and the principal point of thesecond ML correspond to the focal distance of the second ML. Forexample, if pixels are arranged with a pixel pitch of 18 μm, the focaldistance (equivalent value in air) of the first ML is about 65 μm andthe focal distance (equivalent value in air) of the second ML is about40 μm; and the aspheric constant K of each of the first ML and thesecond ML is about −1.3. In addition, the refractive index of the lowrefractive index resin is set in a range of 1.41 to 1.45 and therefractive index of a high refractive index resin to be described lateris set in a range of 1.60 to 1.66. In this case, to satisfy thecondition of field arrangement, the distance (equivalent value in air)between the principal point of the first ML and the principal point ofthe second ML is required to be set to about 40 μm, Accordingly, in thecase of filling a gap between the first and second ML substrates 21 and22 with a high refractive index resin having a refractive index of 1.60in the subsequent step, the thickness of the sealing material 27 may beset to a value capable of ensuring a gap dimension of about 40/1.6=25μm. Concretely, the particle size of plastic beads contained in the sealmaterial 27 may be nearly set to a value calculated from an equation of[25 μm−(D1+D2)] where D1 is the thickness of the low refractive indexresin layer 23 and D2 is the thickness of the low refractive index resinlayer 25 as shown in FIG. 9B. In actual, such determination of thethickness of the seal material 27 must be made in consideration ofdepression of the resin at the time of pressing the resin.

[0137]FIG. 9C shows the step of forming a duel microlens array betweenthe first and second ML substrates. A high refractive index resin 24 isinjected under vacuum in a gap between the first ML substrate 21 and thesecond ML substrate 22 joined to each other by the seal material 27, toform a duel microlens array. In the case of a pixel pitch of 14 μm, analignment accuracy between the first ML substrate 21 and the second MLsubstrate 22 is preferably set in a range of less than ±1.0 μm. The highrefractive index resin 24 injected between the first ML substrate 21 andthe second ML substrate 22 is cured by heating. If the resin 24 is of aUV-cured type resin, the resin 24 is cured by UV irradiation. If needed,the resin 24 may be kept in a liquid state between the first MLsubstrate 21 and the second ML substrate 22.

[0138]FIG. 9D shows the step of removing the second ML substrate bypolishing or grinding. The second ML substrate 22 is removed bypolishing or grinding until the removal depth reaches the protectivefilm 26 functioning as the stopper. Concretely, the second ML substrate22 may be polished by a CMP (Chemical-Mechanical Polishing) processusing, for example, Ce₂O₃. If the protective film 26 is made from a-Si(amorphous silicon), after the a-Si film (protective film) 26functioning as the stopper is exposed by polishing, the a-Si film 26 canbe removed by polishing using silica.

[0139] By the removal of the second ML substrate 22, a structure havingthe DML on the counter substrate side can be obtained. In this step,Since the polishing is performed with the protective film used as thestopper, it is possible to perfectly remove the second ML substrate(cover glass) and also to increase the uniformity of polishing and henceto improve the light utilization efficiency and the image quality.

[0140]FIG. 9E shows the step of finishing a liquid crystal displaydevice. A counter electrode 28 is formed on the surface, exposed bypolishing, of the protective film 26, to obtain a counter substrate 20integrated with the DML. A drive substrate 10 is joined to the countersubstrate 20 via a seal material 31, and liquid crystal 30 is enclosedin a gap therebetween, to obtain a liquid crystal display device. Inaddition, switching devices such as thin film transistors (TFTs) andpixel electrodes are previously integrated on the surface of the drivesubstrate 10.

[0141] As described above, the liquid crystal display device accordingto this embodiment has a panel structure including the drive substrate10 on which at least pixel electrodes and switching devices for drivingthe pixel electrodes are formed, the counter substrate 20 on which atleast the counter electrode 28 is formed, and the liquid crystal layer28 disposed between both the substrates 10 and 20 joined such that thepixel electrodes are opposed to the counter electrode 28 with a specificgap put therebetween. The microlens array composed of the microlensesarranged in a two-dimensional pattern corresponding to the arrangementpattern of the pixel electrodes is assembled at least in the countersubstrate 20.

[0142] As the feature of the liquid crystal display device according tothis embodiment, the microlens array has the back surface joined to thefirst ML substrate 21 constituting the counter substrate 20 and theplanarized front surface.

[0143] The counter electrode 28 is formed on the planarized surface ofthe microlens array via the protective film 26. To be more specific, theprotective film 26 previously formed on the support (second ML substrate22) is bonded on the planarized surface of the microlens array, theprotective film 26 is exposed by removing the support (second MLsubstrate 22), and the counter electrode 28 is formed on the exposedprotective film 26. As described above, the protective film 26 can bemade from Al₂O₃, a-DLC, TiO₂, SiN, or Si.

[0144] According to this embodiment, the microlens array is configuredas a duel microlens array of a double structure having a first microlensarray which is disposed on the side apart from the liquid crystal layer30 and which functions as a condenser lens, and a second microlens arraywhich is disposed on the side close to the liquid crystal layer 30 andwhich functions as an approximately field lens. The distance between theprincipal point of each microlens of the second microlens array and theliquid crystal layer 30 is specified to be in a range of 10 μm or less.

[0145]FIGS. 10A to 10E are process diagrams showing steps of forming aliquid crystal display device as a reference example. In these figures,for an easy understanding, parts corresponding to those of the liquidcrystal display device according to the embodiment shown in FIGS. 9A to9E are denoted by the same reference numerals.

[0146] This reference example is different from the embodiment shown inFIGS. 9A to 9E in that any protective film functioning as a polishingstopper is not interposed between a second ML substrate (cover glass)and a low refractive index resin layer.

[0147] In a step shown in FIG. 10A, a first ML substrate 21 and a secondML substrate 22 are disposed opposite to each other; in a step shown inFIG. 10B, the first ML substrate 21 and the second ML substrate 22 arejoined to each other by a seal material 27; and in a step shown in FIG.10C, a gap between the first ML substrate 21 and the second ML substrate22 joined to each other is filled with a high refractive index resin 24.A duel microlens array is thus formed.

[0148] In a step shown in FIG. 10D, the second ML substrate (coverglass) 22 is removed by polishing or grinding. In this step, asdescribed above, by thinning the thickness of the cover glass to about10 μm, the distance (equivalent value in air) between the principalpoint of the second ML and the surface of the cover glass can besubstantially set to a value in a range of 5 μm or less. However, in thecase of thinning the cover glass to about 10 μm by polishing withoutusing any stopper, since the remaining thickness of the cover glassbecomes too thin, the cover glass may be often obliquely polished asshown in FIG. 10D′, or during the polishing step, the cover glass may becracked, leading to breakage thereof. This causes a variation in lightcollection efficiency or a stray of the boundary between the glass andresin in an image upon projection thereof, to thereby significantlydegrade the image quality.

[0149] In a step shown in FIG. 10E, a counter electrode (not shown) madefrom ITO or the like is formed on the polished surface of the second MLsubstrate 22, to form a counter substrate 20, and the counter substrateis joined to a drive substrate 10 and then liquid crystal 30 is enclosedin a gap therebetween, to obtain a liquid crystal panel. For the liquidcrystal panel thus obtained, if the thickness of the second ML substrate22 is not uniformly polished, such a liquid crystal panel may cause astray of the boundary between the cover glass 22 and the low refractiveindex resin layer 25 in an image upon projection thereof, to therebysignificantly degrade the image quality.

[0150] A second embodiment of the liquid crystal display deviceaccording to the present invention will be described with reference toFIGS. 11A to 11E.

[0151]FIGS. 11A to 11E are process diagrams showing steps of forming aliquid crystal display device in this embodiment.

[0152] This embodiment is characterized in that a dual microlens arrayis formed on the counter substrate side, and that the method of forminga single microlens array (SML) shown in FIGS. 4A to 4D are applied to amethod of forming a duel microlens array.

[0153]FIG. 11A shows the step of forming a first microlens array and asecond microlens array.

[0154] An optical resin layer 23 a is formed on a first support 21 andfirst microlens planes arranged in a two-dimensional pattern are formedon the surface of the optical resin layer 23 a. The irregularities ofthe first microlens planes are filled with an optical resin 23 having arefractive index different from that of the optical resin layer 23 a,and the surface, opposed to the microlens planes, of the optical resin23 is planarized, to thereby form a first microlens array. In thisembodiment, the optical resin 23 used to fill the irregularities of themicrolens planes has a low refractive index such as about 1.4. Thesurface of the optical resin 23 may be planarized by the above-describedstamping method, spin-coating method, or spraying method.

[0155] Similarly, a protective film 26 functioning as a polishingstopper is formed on a second support 22 and an optical resin layer 25 ais formed on the protective film 26, and then second microlens planesarranged in a two-dimensional pattern are formed on the surface of theoptical resin layer 25 a. The irregularities of the second microlensplanes are filled with an optical resin 25 having a refractive indexdifferent from that of the optical resin layer 25 a, and the surface,opposed to the microlens planes, of the optical resin 25 is planarized,to form a second microlens array. The optical resin 25 also has a lowrefractive index of about 1.4. The surface of the optical resin 25filling the microlens planes may be planarized by the above-describedstamping method, spin-coating method, or spraying method.

[0156]FIG. 11B shows the step of overlapping the first and secondmicrolens arrays. An outer peripheral portion of one of the supports 21and 22 is coated with a seal material 27. The supports 21 and 22 arealigned to each other on the basis of alignment marks and overlapped toeach other. The seal material 27 contains a spacer such as high accurateplastic fibers so as to keep the thickness of the seal material 27 in arange of 10 μm or less.

[0157]FIG. 11C shows the step of integrating the first and secondmicrolens arrays with each other. The planarized surface of the firstmicrolens array is joined to the planarized surface of the secondmicrolens array in a state that the first microlens planes are alignedto the second microlens planes, to integrate both the microlens arrayswith each other. As a result, a gap equivalent to the thickness of theseal material 27 is formed between the supports 21 and 22.

[0158]FIG. 11D shows the step of forming a duel microlens array byinjecting a resin in the gap. A high refractive index resin 24 having arefractive index of about 1.6, which resin is in a liquid state, isinjected in the gap specified by the thickness of the seal material 27.The resin 24 is then cured by heating, to form a duel microlens array.It is preferred to very slowly cure the high refractive index resin 24filling the gap in order that stress does not remain in the resin 24.The support 22 is removed by polishing with the protective film 26 usedas the polishing stopper, to expose the surface of the protective film26. A counter electrode made from ITO or the like is formed on thesurface of the exposed protective film 26, to form a counter substrate20.

[0159]FIG. 11E shows the step of finishing a liquid crystal displaydevice. The counter substrate 20 is joined to a previously prepareddrive substrate 10, and liquid crystal is enclosed therebetween. In thisway, a liquid crystal panel is obtained.

[0160] According to this embodiment, since the single microlens arrayseach of which is previously planarized are joined to each other, it ispossible to obtain a high accurate duel microlens array structure withno stress.

[0161]FIG. 12 is a reference diagram showing a general configuration ofa liquid crystal display device having a DML structure in which onemicrolens array is disposed on the counter substrate side and the othermicrolens array is disposed on the drive substrate side. A liquidcrystal display device shown in the figure has a panel structure that adrive substrate 10 and a counter substrate 20 are joined to each otherby a seal material 31 and liquid crystal is enclosed therebetween. Thecounter substrate 20 is composed of a glass substrate 21 and a coverglass 22. A first ML is interposed between the glass substrate 21 andthe cover glass 22, wherein the first ML functions as a condenser lensis located on the incident side. The first ML is formed by stackingresin layers 23 and 24 different in refractive index to each other.

[0162] The drive substrate 10 is generally composed a TFT substrate 11on which thin film transistors and pixel electrodes are integrated. TheTFT substrate 11 is generally thinned by polishing. Pixels 12 areintegrated on the surface of the TFT substrate 11. The pixels 12 arepartitioned from each other by a lattice-shaped black matrix 13. Asecond ML functioning as a field lens is interposed between the TFTsubstrate 11 and an auxiliary substrate on the back side. The second MLis also formed by stacking resin layers 15 and 16 different inrefractive index to each other.

[0163] In the liquid crystal panel having such a DML structure, thethickness {circle over (1)} of the TFT substrate 11 after polishing, thedistance {circle over (2)} between the principal point of the first MLand the principal point of the second ML, and the alignment accuracy{circle over (3)} between the first ML and the second ML are importantfunction parameters.

[0164] The parameter {circle over (2)}, which is the distance betweenthe principal point of the first ML and the principal point of thesecond ML, is required to correspond to the focal distance of the secondML in order to realize the so-called field arrangement. In actual, ifthere is an offset of about 10% between the distance between both theprincipal points and the focal distance of the second ML, the second MLacts as an approximately field lens. For this purpose, the parameter{circle over (1)}, which is the thickness of the TFT substrate 11 afterpolishing, is required to be as small as about 10 to 50 μm.

[0165] With respect to formation of the TFT substrate having such asmall thickness, however, there arise problems that the TFT substratemay cause cracking or chipping during polishing, and also may causestrain or wrinkle due to shrinkage upon curing of a resin duringformation of the second ML.

[0166] As will be described below, such problems can be solved by makinguse of the above-described planarizing technique according to thepresent invention.

[0167] To improve the luminance of a liquid crystal projector, thestructure that one of the microlens arrays of the DML is formed on thedrive substrate side and the other is formed on the counter substrateside as shown in FTG. 9 is superior to the structure that the microlensarrays of the DML are both formed on the counter substrate side.

[0168] In the case of forming the microlens arrays of the DML on thecounter substrate side, although light is effectively collected by themicrolens arrays of the DML, the collected light may be kicked by anon-effective resin such as a black matrix surrounding the pixels on thedrive substrate side, to reduce the effective aperture ratio. On thecontrary, in the structure that one of the microlens arrays of the DMLis disposed on the drive substrate side and the other is disposed on thecounter substrate side, by shortening the focal distance of the firstML, it is allowed for light emitted from a light source to be collectedas much as possible, and it is allowed for such a large quantity ofcollected light to pass through pixel apertures on the TFT substrateside. Meanwhile, the second ML is disposed as a field lens while beingopposed to the first ML with the TFT substrate put therebetween in sucha manner that the principal point of the second ML is apart from theprincipal point of the first ML by the focal distance of the second ML.

[0169] A third embodiment of the liquid crystal display device accordingto the present invention will be described with reference to FIGS. 13Ato 13F.

[0170]FIGS. 13A to 13F are process diagrams showing steps of forming aliquid crystal display device in this embodiment.

[0171] This embodiment is characterized in that one of microlens arraysof a DML structure is disposed on the drive substrate side and the otheris disposed on the counter substrate side.

[0172]FIG. 13A shows the step of preparing a TFT substrate. A TFTsubstrate 11 on which TFTs and pixel electrodes are previously formed isprepared. In the figure, only a black matrix 13 for partitioning pixelsfrom each other is shown, with TFTs and pixel electrodes not shown.

[0173]FIG. 13B shows the step of sticking a base glass to the TFTsubstrate. A base glass 40 is stuck on the surface of the TFT substrate11 via an adhesive 41 such as wax.

[0174]FIG. 13C shows the step of polishing the TFT substrate. The backsurface of the TFT substrate 11 in a state being held by the base glass40 is polished to a thickness of 20 μm or less.

[0175]FIG. 130 shows the step of preparing a glass substrate with asecond ML. A glass substrate 14 on which a second ML is previouslyformed is prepared. The second ML has a structure formed by stackingresin layers 15 and 16 different in refractive index to each other. Thesurface, opposed to microlens planes, of the second resin layer 16 isplanarized by the above-described stamping method or spin-coatingmethod. A peripheral portion of the polished back surface of the TFTsubstrate 11 is coated with a seal material 18 having a thickness of 2to 3 μm.

[0176]FIG. 13E shows the step of forming a drive substrate by joiningthe TFT substrate to the glass substrate. In a state that pixels formedon the TFT substrate 11 side are aligned to the second ML formed on theglass substrate 14 side, the TFT substrate 11 is overlapped to the glasssubstrate 14. A gap between both the overlapped substrates 14 and 11 isfilled with an adhesive 19, to join both the substrates 14 and 11 toeach other. Here, since the planarized surface of the second ML isjoined to the polished back surface of the TFT substrate 11, it ispossible to solve the related art problem associated with stress. Adrive substrate 10 integrated with the second ML is thus obtained. Sincethen, the unnecessary base glass 40 is removed, and the adhesive such aswax remaining on the surface of the TFT substrate 11 is separated.

[0177]FIG. 13F shows the step of finishing a liquid crystal displaydevice. A counter substrate 20 to which a first ML is previouslyintegrated is prepared. The counter substrate 20 includes a glasssubstrate 21, a cover glass 22, and the first ML held therebetween. Thefirst ML has a stacked structure formed by stacking resin layers 23 and24 different in refractive index to each other. The counter substrate 20integrated with the first ML is joined to the drive substrate 10integrated with the second ML, and liquid crystal is enclosed in a gaptherebetween, to obtain a liquid crystal display device. The first MLincorporated in the counter substrate 20 functions as a condenser lens,and the second ML formed on the drive substrate 10 functions as a fieldlens.

[0178] As described above, the liquid crystal display device shown inFIGS. 13A to 13F has the panel structure including the drive substrate10 on which at least pixels electrodes and the switching devices fordriving the pixel electrodes are formed, the counter substrate 20 onwhich at least a counter electrode is formed, and the liquid crystallayer disposed between both the substrates 10 and 20 joined such thatthe pixels electrodes are opposed to the counter electrode with aspecific gap kept therebetween.

[0179] The microlens array composed of microlenses arranged in atwo-dimensional pattern corresponding to the arrangement pitch of thepixel electrodes is incorporated at least in the drive substrate 10. Themicrolens array (second ML) has the stacked structure including thefirst optical resin layer 15 which has a first refractive index andwhich has the microlens planes arranged in a two-dimensional pattern,and the second optical resin layer 16 which has a second refractiveindex and which fills the irregularities of the microlens planes and hasthe planarized surface. The microlens array (second ML) is joined to theTFT substrate 11 such that the planarized surface of the second opticalresin layer 16 is in contact with the back surface of the TFT substrate11. The microlens array (second ML) is obtained by filling the microlensplanes of the first optical resin layer 15 with the resin (for formingthe second optical resin layer 16) and pressing the surface of the resinwith a stamper having a flat plane, to planarize the surface, opposed tothe microlens planes, of the second optical resin layer 16.Alternatively, the planarization may be performed by making use of theabove-described polishing technique in place of stamping using thestamper. The polishing technique includes the steps of joining a supportlayer, on which a protective layer as a polishing stopper is previouslyformed, to the first optical resin layer with a specific gap kepttherebetween; filling the gap with a liquid resin and curing the resin,to form the second optical resin layer; and removing the support layerby polishing, to expose the protective layer. In this technique, theexposed surface of the protective layer is taken as the planarizedsurface of the second optical resin layer.

[0180] According to this embodiment, the microlens array (first ML) isdisposed in the counter substrate 20 in such a manner as to be matchedwith the microlens array (second ML) disposed in the drive substrate.The microlens array (first ML) functions as a condenser lens and themicrolens array (second ML) functions as a field lens. The TFT substrate11 of the drive substrate 10 is polished from the back side to bethinned. The planarized surface of the second optical resin layer 16 ofthe microlens array (second ML) is joined to the polished back surfaceof the TFT substrate 11.

[0181]FIG. 14A is a typical sectional view showing a finished state ofthe liquid crystal display device shown in FIGS. 13A to 13F, and FIG.14B is a partial enlarged view of FIG. 14A.

[0182] As described above, the second ML is joined to the polished backsurface of the TFT substrate 11 via a thin layer of the adhesive 19.Here, it is particularly important to join the previously planarizedsurface of the second ML to the back surface of the thinned TFTsubstrate 11.

[0183] For example, in the case where the TFT substrate 11 is used for a0.7 inch TFT substrate (pixel pitch: 18 μm) for SVGA (Super VideoGraphics Array), if the focal distance (equivalent value in air) of afirst ML is about 35 μm and the focal distance (equivalent value in air)of a second ML is about 42 μm, the distance (equivalent value in air)between the principal point of the first ML and the interface of aliquid crystal layer 30 is about 20 μm, the thickness (equivalent valuein air) of the liquid crystal layer 30 is 2 μm, and the distance(equivalent value in air) between the interface of a liquid crystallayer 30 and the principal point of the second ML is about 20 μm. Inthis case, the thickness of the TFT substrate 11 is thinned by polishingto an actual thickness of about 27 μm (equivalent value in air: about 18μm). In this way, the TFT substrate 11 is very thin, and therefore, if ahigh refractive index resin 16 is solidified by UV-curing or thermalcuring in a state being in contact with the TFT substrate 11 as in therelated art method, the TFT substrate 11 causes strain due to stressgenerated upon curing. Such strain exerts adverse effect on the imagequality.

[0184] To cope with such an inconvenience, according to the presentinvention, the previously planarized surface of the second ML is stuckon the back surface of the TFT substrate 11, to thereby suppressoccurrence of stress.

[0185] As shown in FIG. 14B, the thicknesses of the resin layer 16 ofthe second ML are different at locations A, B and C. If the second ML isjoined to the TFT substrate 11 in a state that the surface of the resinlayer 16 is not planarized, the shrinkage volume of the resin layer 16upon curing locally differs, to cause strain in the TFT substrate 11.

[0186] A fourth embodiment of the liquid crystal display deviceaccording to the present invention will be described with reference toFIGS. 15A to 15F.

[0187]FIGS. 15A to 15F are process diagrams showing steps of forming aliquid crystal display device in this embodiment.

[0188] This embodiment is characterized in that one of microlens arraysof a DML structure is disposed on the drive substrate side and the otheris disposed on the counter substrate side.

[0189]FIG. 15A shows the step of preparing a finished liquid crystalpanel. A finished liquid crystal panel 50, which has a stacked structureformed by stacking a counter substrate 20 to a TFT substrate 11 andenclosing liquid crystal 30 therebetween, is prepared. The countersubstrate 20 has a thickness of, for example, 1.1 mm and incorporates afirst ML. The TFT substrate 11 has a thickness of 0.8 to 1.2 mm, on thesurface of which TFTs and pixel electrodes are integrated.

[0190]FIG. 15B shows the step of stacking a jig to the countersubstrate. A jig 40 made from blue plate glass is stuck on the countersubstrate 20 side with wax.

[0191]FIG. 15C shows the step of polishing the TFT substrate. In a statethat the panel is held by the jig 40, the back surface of the TFTsubstrate 11 is polished until the thickness of the TFT substrate 11becomes about 10 to 20 μm.

[0192]FIG. 15D shows the step of preparing a glass substrate having asecond ML. A peripheral portion of the polished back surface of the TFTsubstrate 11 is coated with a seal material 18, and at the same time, aglass substrate 14 on which a second ML is previously formed isprepared. The second ML has a stacked structure formed by stackingoptical resin layers 15 and 16 different in refractive index to eachother.

[0193]FIG. 15E shows the step of joining the liquid crystal panel to theglass substrate. The liquid crystal 50 is aligned to the glass substrate14, and is then joined thereto via the adhesive (seal material) 18. Atthis time, the glass substrate 14 integrated with the second ML isjoined to the polished back surface of the TFT substrate 11, to form adrive substrate 10. A high refractive index resin 19 is injected in agap between the TFT substrate 11 and the planarized surface of thesecond ML.

[0194]FIG. 15F shows the step of removing the jig. The unnecessary jig40 is finally removed.

[0195] A panel having a structure that the counter substrate 20integrated with the first ML is joined to the drive substrate 10incorporating the second ML, and the liquid crystal 30 is enclosedtherebetween is thus obtained. With this panel, since the surface of thesecond ML is planarized and the thickness of the resin layer 19 is asvery thin as comparable to that of the liquid crystal layer 30, it ispossible to prevent occurrence of stress due to shrinkage upon curingthe resin.

[0196] A fifth embodiment of the liquid crystal display device accordingto the present invention will be described with reference to FIG. 16.

[0197]FIG. 16 is a typical sectional view showing opticalcharacteristics of a liquid crystal display device in this embodiment,which has a panel structure that one of a pair of microlens arrays isdisposed on the counter substrate side and the other is disposed on thedrive substrate side. To be more specific, lens planes having a lightcondensing function are disposed on the counter substrate side, and lensplanes having a field function are disposed on the TFT substrate (drivesubstrate) side. The liquid crystal panel includes a TFT substrate 50B,and a counter substrate 50A disposed on the light incident plane side ofthe TFT substrate 50B in such a manner as to be opposed to the TFTsubstrate 50B with a liquid crystal layer 45 put therebetween.

[0198] The counter substrate 50A has a glass substrate 41, a resin layer43A, a first microlens array 42A, and a thinned counter substrate 44A,which are arranged in this order from the light incident side. The TFTsubstrate SOB has pixel electrodes 46, a black matrix 47, a thinned TFTsubstrate 44B, a second microlens array 42B, a resin layer 43B, and aglass substrate 48, which are arranged in this order from the lightincident side.

[0199] The first microlens array 42A is made from an optical resin, andhas a plurality of first microlens 42M-1 arranged in a two-dimensionalpattern corresponding to an arrangement pattern of the pixel electrodes46. Each mirolens 42M-1 has a first lens plane RI having a positivepower and functions as a condenser lens. In this embodiment, arefractive index n1 of the resin layer 43A and a refractive index n2 ofthe first microlens array 42A satisfy a relation of n2>n1, and the firstlens plane R1 is convex toward the light incident side (light sourceside) Like the first microlens array 42A, the second microlens array 42Bis made from an optical resin, and has a plurality of second microlenses42M-2 arranged in a two-dimensional pattern corresponding to anarrangement pattern of the pixel electrodes 46. Each microlens 42M-2 hasa second lens plane R2 having a positive power and functions as a fieldlens. Accordingly, the focal point of the second lens plane R2 of thesecond microlens 42M-2 nearly corresponds to the principal point of thefirst lens plane R1 of the first microlens 42M-1 (see an optical pathshown by a dotted line in the figure). In this embodiment, a refractiveindex n4 of the resin layer 43B and a refractive index n3 of the secondmicrolens array 42B satisfy a relation of n4>n3, and the second lensplane R2 is convex toward the light incident side.

[0200] A duel microlens array in this embodiment has a structure thateach pixel aperture is positioned between both the microlenses 42M-1 and42M-2, more specifically, between both the lens planes R1 and R2. On anoptical axis 60, the synthesized focal point of both the microlenses42M-1 and 42M-2 is located near the pixel aperture (see an optical pathshown by a solid line in the figure). The alignment of the synthesizedfocal point to the pixel aperture can be controlled by adjusting thethickness between each of the microlenses 42M-1 and 42M-2 and the pixelaperture. Such a configuration is best for enhancing the effectiveaperture ratio; however, it has been regarded to be produced with themost difficulty. According to the present invention, it is possible toovercome such a difficulty in production and to realize the duelmicrolens array structure shown in the figure.

[0201] A sixth embodiment of the liquid crystal display device accordingto the present invention will be described with reference to FIG. 17.

[0202]FIG. 17 is a typical sectional view showing the entireconfiguration of a liquid crystal display device having a panelstructure in this embodiment.

[0203] This embodiment is characterized by realizing a small-sizedliquid crystal panel with a high definition characteristic.

[0204] A liquid crystal panel shown in the figure is configured suchthat a counter substrate 20 is stuck on a drive substrate 10 with aspecific gap kept therebetween and liquid crystal 30 is enclosed in thegap. As described above, a microlens ML functioning as a condenser lensis formed in the counter substrate 20, and a microlens ML functioning asa field lens is integrated to the drive substrate 10.

[0205] Scanning lines 104 and signal lines 105, which are perpendicularto each other, are provided on the inner surface of the drive substrate10. Pixel electrode 106 and thin film transistors (TFt) as pixelswitches are arranged in a matrix at respective intersections at whichthe lines 104 and 105 cross each other. While not shown, an alignmentfilm having been subjected to rubbing treatment is formed on the innersurface of the drive substrate 10. A counter electrode 112 is formed onthe inner surface of the counter substrate 20. While not shown, analignment film having been subjected to rubbing treatment is alsoprovided on the inner surface of the counter electrode 112.

[0206] Polarizing plates 110 and 111 are disposed on both the outersides of the assembly of the drive substrate 10 and the countersubstrate 20 joined to each other, wherein the polarizing plate 110 islocated on the drive substrate 10 side with a specific gap kepttherebetween and the polarizing plate 111 is located on the countersubstrate 20 side with a specific gap kept therebetween. A scanningpulse is applied to a scanning line 104, to select the TFTs along thescanning line 104, and a signal is supplied to a signal line 105, to bewritten on the pixel electrode 106 located at the intersection betweenthe scanning line 104 and the signal line 105. A voltage is appliedbetween such a pixel electrode 106 and the counter electrode 112, toactivate the liquid crystal 30. A change in transmission amount ofincident white light due to activation of the liquid crystal layer 30 istaken out through a pair of the polarizing plates 110 and 111 set in across nicol position, to perform a desired image display.

[0207] A projector is configured by projecting such an image display toa screen located in front of the liquid crystal panel via an enlargedprojection optical system. If such a projector adopts a duel microlensarray structure having a combination of the microlens array functioningas a condenser lens and the microlens array functioning as a field lens,it is expected to improve the utilization efficiency of light emittedfrom a light source and to obtain a screen with a high luminance.

[0208] The projector to which the present invention is applied will bedescribed below.

[0209] 3. Projector

[0210] An embodiment of a projector of the present invention will bedescribed with reference to FIG. 18. FIG. 18 is a typical diagramshowing a projector incorporating the liquid crystal panel shown in FIG.17. The projector shown in the figure is of a so-called three-panel typein which a color image display is performed by using three pieces oftransmission type liquid crystal panels, wherein each liquid panelincorporates a microlens array configured according to the presentinvention.

[0211] The projector in this embodiment includes a light source 211, apair of first and second multi-lens array integrators 212 and 213, and afull-reflection mirror 214 disposed between the first and secondmulti-lens array integrators 212 and 213 in such a manner that anoptical path (optical axis 210) is turned at an approximately 90° on thesecond multi-lens array integrator 213 side. A plurality of microlenses212M are arranged in a two-dimensional pattern in the first multi-lensarray integrator 212, and similarly a plurality of microlenses 213M arearranged in a two-dimensional pattern in the second multi-lens arrayintegrator 213. Each of the multi-lens array integrators 212 and 213 isintended to equalize a light illuminance distribution, and has afunction of dividing incident light into a plurality of small lightfluxes.

[0212] The light source 211 emits white light containing a red lightcomponent, a blue right component, and a green light component requiredfor color image display. The light source 211 is composed of an emitter(not shown) for emitting light, and a concave mirror for reflecting andcollecting the light emitted from the emitter. Examples of the emittersinclude a halogen lamp, a metal lamp, and a xenon lamp. The concavemirror preferably has a shape capable of enhancing the light collectionefficiency, for example, a rotation-symmetric shape such as an ellipsoidof revolution or a paraboloid of revolution.

[0213] The projector also includes a PS synthesizing element 215, acondenser lens 216, and a dichroic mirror 217 arranged in this order onthe light emergence side of the second multi-lens array integrator 213side. The dichroic mirror 217 has a function of separating incidentlight, for example, into a red light component LR and the other colorlight component.

[0214] The PS synthesizing element 215 is provided with a plurality ofhalf-wave plates 215A at positions each of which corresponds to a gapbetween adjacent two of the microlenses of the second multi-lens arrayintegrator 213. The PS synthesizing element 215 has a function ofseparating incident light LO into two kinds of polarized lightcomponents (P-polarized light component and S-polarized light component)L1 and L2. The PS synthesizing element 215 also has a function of makingthe polarized light component L2 (for example, P-polarized lightcomponent) emergent from the PS synthesizing element 215 while keepingthe polarization direction thereof, and converting the polarized lightcomponent L1 (for example, S-polarized light component) into the otherpolarized light component (for example, P-polarized light component) bythe function of the half-wave plates 215A.

[0215] The projector also includes a full-reflection mirror 218, a fieldlens 224R, and a liquid crystal panel 225R in this order along anoptical path of the red light component LR separated by the diachronicmirror 217. The full-reflection mirror 218 reflects the red lightcomponent LR separated by the dichroic mirror 217 to the liquid crystalpanel 225R. The liquid crystal panel 225R has a function of spatiallymodulating the red light component LR made incident thereon via thefield lens 224R on the basis of an image signal.

[0216] The projector also includes a dichroic mirror 219 along anoptical path of the other color light component separated by thedichroic mirror 217. The dichroic mirror 219 has a function ofseparating the other color light component made incident thereon, forexample, into a green light component LG and a blue light component LB.

[0217] The projector also includes a field lens 224G and a liquidcrystal panel 225G arranged in this order along an optical path of thegreen light component LG separated by the dichroic mirror 219. Theliquid crystal panel 225G has a function of spatially modulating thegreen light component LG made incident thereon via the field lens 224Gon the basis of an image signal.

[0218] The projector also includes a relay lens 220, a full-reflectionmirror 221, a relay lens 222, a full-reflection mirror 223, a field lens224B, and a liquid crystal panel 225B arranged in this order along anoptical path of the blue light component LB separated by the dichroicmirror 219. The full-reflection mirror 221 reflects the blue lightcomponent LB made incident thereon via the relay lens 220 to thefull-reflection mirror 223. The full-reflection mirror 223 reflects theblue light component LB, which has been reflected from thefull-reflection mirror 221 and made incident thereon via the relay lens222, to the liquid crystal panel 225B. The liquid crystal panel 225B hasa function of spatially modulating the blue light component LB, whichhas been reflected from the full-reflection mirror 223 and made incidentthereon via the field lens 224B, on the basis of an image signal.

[0219] The projector also includes, at a position at which the opticalpaths of the red light component LR, the green light component LG, andthe blue light component LB cross each other, a cross-prism 226 having afunction of synthesizing the three color light components LR, LG, andLB. The projector also includes a projection lens 227 for projecting thesynthesized light emerged from the cross-prism 226 to a screen 228. Thecross-prism 226 has three incident planes 226R, 226G, and 226B, and oneemergence plane 226T. The red light component LR emergent from theliquid crystal panel 225R is made incident on the incident plane 226R;the green light component LG emergent from the liquid crystal panel 225Gis made incident on the liquid crystal panel 226B; and the blue lightcomponent LB emergent from the liquid crystal panel 225B is madeincident on the incident plane 226B. The cross-prism 226 synthesizes thethree color light components made incident on the incident planes 226R,226G, and 226Br and makes the synthesized light emergent from theemergence plane 226T.

[0220] 4. Production of Liquid Crystal Display Device

[0221] A first embodiment of a method of producing a liquid crystaldisplay device according to the present invention will be described withreference to FIGS. 19A to 19E.

[0222]FIGS. 19A to 19E are process diagrams showing basic steps ofproducing a liquid crystal display device according to this embodiment.

[0223]FIG. 19A shows a step of bonding a TFT substrate to a base glass.A base plate such as a base glass 1002 is bonded on a front surface 1001f of a TFT substrate 1001 via an adhesive 1003 soluble in water or anorganic solvent.

[0224] Examples of the adhesives 1003 include a wax such as a hot melttype water-soluble solid wax or a water-soluble liquid wax, athermoplastic polymer adhesive (trade name: Crystal Bond), acyanoacrylate based adhesive, and an epoxy based adhesive.

[0225] The hot melt type water-soluble solid wax is available from, forexample, Nikka Seiko Co., Ltd. under the trade names of “Aqua Wax20/50/80” (main component: fatty acid glyceride), “Aqua Wax553/531/442/SE” (main component: polyethylene glycol, vinyl pyrrolidonecopolymer, glycerine polyether), and “PEG Wax 20” (main component:polyethylene glycol).

[0226] The water-soluble liquid wax is available as a synthetic resinbased liquid adhesive from, for example, Nikka Seiko Co., Ltd. under thetrade names of “Aqua Liquid WA-302 (main component: polyethylene glycol,polyvinyl pyrrolidone derivative, methanol), and WA-20511/QA-20566 (maincomponent; polyethylene glycol, polyvinyl pyrrolidone derivative, IPA(isopropyl alchol), water).

[0227] The base glass 1002 may be stuck on the TFT substrate 1001 bymeans of a UV-cured type adhesive double-coated tape or athermally-cured type adhesive double-coated tape.

[0228] If needed, to protect the surface of the TFT substrate 1001 orprevent contamination of the surface of the TFT substrate 1001 withhalogen ions, the front surface 1001 f of the TFT substrate 1001 may becoated with a resist film. In addition, the base glass material may be atransparent glass such as borosilicate glass or blue plate glass.

[0229] In the case of using the thermoplastic polymer adhesive (tradename: Crystal Bond) soluble in an organic solvent such as acetone as theadhesive 1003, the bonding step may be performed by coating the baseglass 1002 with the crystal bond dissolved in acetone; overlapping theTFT substrate 1001 to the base glass 1002; heating the TFT substrate1001 and the base glass 1002 overlapped to each other in vacuum under acondition with 150-160° C./13.3322 Pa (0.1 Torr), to remove bubblesinterposed therebetween, thereby bringing the TFT substrate 1001 intoclose-contact with the base glass 1002; and breaking the vacuum, topromote the degassing with the pressure generated upon return toatmospheric pressure and to equalize the thickness of the adhesive 1003,for example, to 1 to 3 μm.

[0230] In the case of using the hot melt type water-soluble solid wax(for example, “Aqua Wax 80/553” or “PEG Wax 20” available from NikkaSeiko Co., Ltd.) as the adhesive 1003, the bonding step may be performedby dissolving 30 to 40 wt % of the wax in methanol and filtering the waxsolution to remove foreign matters; coating the base glass 1002 with thewax solution by spin-coating; overlapping the TFT substrate 1001 to thebase glass 1002; heating the TFT substrate 1001 and the base glass 1002overlapped to each other in vacuum under a condition with 80-100°C./13.3322 Pa (0.1 Torr), to remove bubbles interposed therebetween,thereby bringing the TPT substrate 1001 into close-contact with the baseglass 1002; and breaking the vacuum, to promote the degassing with thepressure generated upon return to atmospheric pressure and to equalizethe thickness of the adhesive 1003, for example, to 1 to 3 μm.

[0231] In the case of using the water-soluble liquid wax (for example,“Aqua Liquid WA-302” available from Nikka Seiko Co., Ltd.) as theadhesive 1003, the bonding step may be performed by coating the baseglass 1002 with the liquid wax having a viscosity of, for example, 4 to5 cps by spin-coating; overlapping the TFT substrate 1001 to the baseglass 1002; heating the TFT substrate 1001 and the base glass 1002overlapped to each other in vacuum under a condition with 70-80°C./13.3322 Pa (0.1 Torr), to remove bubbles interposed therebetween,thereby bringing the TFT substrate 1001 into close-contact with the baseglass 1002; and breaking the vacuum, to promote the degassing with thepressure generated upon return to atmospheric pressure and to equalizethe thickness of the adhesive 1003, for example, to 1 to 3 μm.

[0232] In the case of using the double-coated tape as the adhesive 1003,the bonding step may be performed by bonding the base glass 1002 to theTFT substrate 1001 by using a polyolefine tape (thickness: 100±2 μm)with its both surfaces coated with an UV-cured type adhesive (thickness:10±1 μm) or a polyolefine tape (thickness: 100±2 μm) with its bothsurfaces coated with a thermally-cured type adhesive. In this step,vacuum degassing treatment may be performed to prevent occurrence ofbubbles therebetween.

[0233]FIG. 19B shows the step of polishing the TFT substrate. In a statethat the TFT substrate 1001 is held by the base glass 1002, a backsurface 1001 b of the TFT substrate 1001 is polished to be thinned. Forexample, the back surface 1001 b of the TFT substrate 1001 is polishedby a method of polishing one surface with a grade suitable for opticswhile the base glass 1002 is taken as a reference plane, to prepare theTFT thin substrate 1001 having a specific thickness (for example, 20±3μm). As the dimensional accuracy of the base glass 1002, the parallelismis set to 1 to 3 μm and the thickness is 2 mm.

[0234] The method for one-surface polishing with a grade suitable foroptics may be performed by one-surface buffing made in the order ofrough buffing, medium buffing, and finish buffing, wherein particlesizes of abrasives such as alumina or cerium oxide may be reduced in theorder of the rough buffing, medium buffing, and finish buffing, tothereby gradually increase the polishing accuracy.

[0235] The one-surface buffing performed as the method for one-surfacepolishing with a grade suitable for optics may be combined withone-surface blasting. This one-surface blasting involves preparing alaminar flow of high pressure air in which particles of abrasives suchas silicon carbide, boron carbide, or diamond are dispersed, andblasting a specific amount of the laminar flow from a slit-shapedopening at the leading end of a nozzle while scanning the nozzle in thereciprocating directions over the back surface 1001 b of the TFTsubstrate 1001, to polish the back surface 1001 b of the TFT substrate1001. The blasting is followed by finish polishing, that is, finishbuffing, to further increase the polishing accuracy and remove residualstress due to blasting of the particles.

[0236] The method for one-surface polishing with a grade suitable foroptics may be performed by CMP (Chemical Mechanical Polishing). Like theone-surface buffing, the CMP may be performed in the order of roughpolishing, medium polishing, and finish polishing.

[0237] The one-surface buffing performed as the method for one-surfacepolishing with a grade suitable for optics may be combined with a methodfor one-surface etching with a grade suitable for glass. This processinvolves reducing the thickness of the TFT substrate 1001 to a specificvalue by the method for etching with a grade for glass, and removingsurface waviness due to the method for etching with a grade suitable forglass by finish buffing performed as the method for polishing with agrade suitable for optics. In this case, it is required to use aprotective adhesive or tape withstanding a hydrofluoric acid basedetchant.

[0238] The one-surface CMP performed as the method for one-surfacepolishing with a grade suitable for optics may be combined with themethod for one-surface etching with a grade suitable for optics. Thisprocess involves etching the back surface 1001 b of the TFT substrate1001 made from quartz glass to a specific value with a hydrofluoric acidbased etchant, and removing surface waviness due to glass etching by CMPperformed as the method for polishing with a grade suitable for optics.Even in this case, it is required to use a protective adhesive or tapewithstanding a hydrofluoric acid based etchant.

[0239]FIG. 19C shows the step of sticking a microlens array on the TFTsubstrate. A microlens array is stuck on the polished back surface 1001b of the TFT substrate 1001 via an optical resin 1005. To be morespecific, this step includes a step of preparing a microlens substrate(ML substrate) 1004 in which microlens planes 1004 r are arranged in atwo-dimensional pattern by processing an optical glass such as quartzglass or crystallized glass (Neo Ceram), and a step of aligning andoverlapping the ML substrate 1004 to the polished back surface 1001 b ofthe TFT substrate 1001, filling a gap therebetween with a transparentoptical resin 1005 having a refractive index higher than that of each ofthe substrates 1001 and 1004, and curing the optical resin 1005. In thiscase, the closed gap is formed between the TFT substrate 1001 and the MLsubstrate 1004 by bonding the ML substrate 1004 to the back surface 1001b of the TFT substrate 1001 via a seal material 1006, and is then filledwith the transparent high refractive index optical resin 1005 The latterfilling/curing step will be more fully described below.

[0240] A frame made from the seal material 1006 and having a fillingport is formed around the ML substrate (microlens substrate) 1004, andthe TFT substrate 1001 thinned by polishing is overlapped to the MLsubstrate 1004. In this state, the seal material is cured. If the sealmaterial 1006 is composed of a thermally-cured type adhesive, it iscured by heating at a specific temperature, whereas if the seal material1006 is composed of an UV-cured type adhesive, it is cured byUV-irradiation with a specific energy. Alternatively, if the sealmaterial 1006 is composed of a thermally-cured/UV-cured combination typeadhesive, it is cured by combination of heating at a specifictemperature and UV-irradiation with a specific energy.

[0241] The high refractive index transparent optical resin 1005 isinjected in the gap from the filling port, and the filling port issealed with a UV-cured type adhesive. The optical resin 1005 is thenthermally cured. In the case of using an acrylic based or an acrylicepoxy based high refractive index transparent resin (viscosity: 20 to100 cps) as the optical resin 1005, the filling port is dispense-coatedwith the resin or dipped in the resin in vacuum, and is injected in thegap through the filling port with a pressure upon return to atmosphericpressure. At this time, a suitable pressure may be added to inject theresin in the gap through the filling port. Such a high refractive indextransparent resin is then cured at a temperature of 70 to 80° C. for 120min, to obtain the high refractive index transparent optical resin 1005having a refractive index of 1.59 to 1.67.

[0242] Since the high refractive index optical resin 1005 is injected inthe lens planes 1004 r formed in the microlens substrate 1004 having arelatively low refractive index and is cured, the microlenses can beautomatically formed. In addition, to align the lens planes 1004 r onthe microlens substrate 1004 side to pixel electrodes an the TFTsubstrate 1001 side in one-to-one relationship, the TFT substrate andthe ML substrate are overlapped to each other with alignment marksformed on both the TFT substrate and the ML substrate aligned to eachother, and are fixed by the seal material 1006.

[0243]FIG. 19D shows the step of peeling the base glass. A spent baseglass 1002 is peeled from the front surface 1001 f of the TFT substrate1001, to integrate the microlens array with the back surface 1001 b ofthe TFT substrate 1001. Concretely, the base glass can be peeled fromthe TFT substrate 1001 by heating or UV irradiation. In the case ofusing a thermoplastic polymer (crystal bond) or a cyanoacrylate basedadhesive as the adhesive 1003, after the base glass is peeled byheating, the entire ML substrate is subjected to ultrasonic cleaningusing an organic solvent such as acetone, a combination of acetone andethanol, methanol, or IPA. In the case of using a hot melt basedwater-soluble wax (for example, “Aqua Wax 80/553” or “PEG Wax 20”available from Nikka Seiko Co., Ltd.) as the adhesive 1003, the entireML substrate is subjected to ultrasonic cleaning using pure water or hotpure water at 50 to 60° C. In addition, the spent high accurate baseglass is desirable to be re-used after being cleaned.

[0244]FIG. 19E shows the step of finishing a liquid crystal displaydevice. A microlens TFT substrate (MLTFT substrate) 1007 obtained byintegrating the one-surface polished TFT substrate 1001 with themicrolens substrate 1004 is overlapped to a microlens counter substrate(ML counter substrate) 1017 obtained by integrating a microlenssubstrate with a counter substrate with a specific gap kepttherebetween, and the gap is filled with liquid crystal 1009 and is thensealed, to obtain an active matrix type liquid crystal display devicehaving a dual microlens structure.

[0245] The microlens counter substrate 1017 can be obtained in the samesteps as those for the microlens TFT substrate 1007. To be morespecific, the front surface side of a counter substrate 1011 ispolished, and a microlens substrate 1014 is stuck on the polishedsurface of the counter substrate 1011 via a seal material 1016.Microlens planes 1014 r are previously formed on the microlens substrate1014. A gap between the single-surface polished counter substrate 1011and the microlens substrate 1014 is filled with a high refractive indextransparent optical resin 1015 and is cured, to obtain the ML countersubstrate 1017. In addition, a counter electrode is previously formed onthe front surface, to be brought into contact with the liquid crystal1009, of the counter substrate 1011.

[0246] The liquid crystal display device produced by the productionmethod according to this embodiment has a panel structure that theliquid crystal 1009 is held between the pixel electrodes formed on theMLTFT substrate 1007 side and the counter electrode formed on the MLcounter substrate 1017 side. The microlens array in which microlensesfunctioning as condenser lenses for respective pixel electrodes arearranged in two-dimensional pattern is integrally formed on the MLcounter substrate 1017 side. The microlens array in which microlensesfunctioning as field lenses for respective pixel electrodes are arrangedin a two-dimensional pattern is integrally formed on the MLTFT substrate1007 side.

[0247] In the above-described polishing step, the TFT substrate 1001and/or the counter substrate 1011 are polished to reduce the thicknessesin such a manner that the focal point of each microlens functioning asthe field lens nearly corresponds to the principal point of thecorresponding microlens functioning as the condenser lens in thefinished panel state. For example, according to this embodiment, sincethe TFT substrate 1001 is thinned to a thickness of about 20 μm, theabove requirement can be satisfied. By arranging microlens arrays onboth the TFT substrate 1001 side and the counter substrate loll sidesuch that the focal point of each field lens nearly corresponds to theprincipal point of the condenser lens, it is possible to enlarge theeffective aperture ratio of the pixels at maximum.

[0248] Along with the tendency toward finer pixels, the focal point ofeach microlens tends to become shorter, and correspondingly, it isrequired to reduce the thickness of each substrate to significantdegree. From this viewpoint, the production method of the presentinvention is advantageous in rationally, efficiently thinning each ofthe TFT substrate and the counter substrate.

[0249] The lens planes 1004 r and 1014 r of the microlenses can be eachformed into the spheric, aspheric, or Fresnel plane. The spheric lens isadvantageous in easy production; however, since the radius of curvatureof the lens, which is capable of making the focal distance shortest, islimited to the pixel size, it is difficult to shorten the focal distanceunless the difference in refractive index at the interface between thelens planes can be sufficiently ensured. Each of the aspheric andFresnel lenses is excellent in shortening of the focal distance andplanarity of the lens principal plane, and is very effective to suppressthe divergence angle of light emitted from a light source.

[0250] A second embodiment of the method of producing a liquid crystaldisplay device according to the present invention will be described withreference to FIG. 20.

[0251]FIG. 20 is a process diagram showing the steps of producing theliquid crystal display device in this embodiment, wherein a multi-chipmodule process is performed in steps S1 to S6 and a single-chip moduleprocess is performed in step S7 and S8, with ML counter substrates(single-chip module substrates) prepared between steps S7 and S8.

[0252] In this embodiment, a large area TFT substrate (TFT large-sizedsubstrate) is used as a multi-chip module substrate for promotingrationalization of the production process. To be more specific, thelarge area substrate (multi-chip module substrate) is used in steps S1to S6, and is divided into single substrates (single-chip modulesubstrates) corresponding to individual panels in step S7.

[0253] In step S1, a TFT large-sized substrate having a diameter of, forexample, 8 inches is prepared. In step S2, a base glass having adiameter of 8 inches is stuck on the TFT large-sized substrate. In stepS3, the thickness of the TFT large-sized substrate is reduced to 20 μmby the method for one-surface polishing with a grade suitable foroptics. In step S4, an ML substrate (diameter: 8 inches) in whichmicrolens planes are previously formed is stuck on the polished surfaceof the TFT large-sized substrate by a seal material, and the microlensplanes are filled with a high refractive index resin to form a microlensarray therebetween. In step S5, the spent base glass is peeled and theTFT large-sized substrate is cleaned.

[0254] In step S6, the exposed surface of the TFT large-sized substrateis subjected to alignment treatment. For Example, a polyimide alignmentfilm is formed on the surface of the TFT large-sized substrate and issubjected to rubbing treatment. In this case, since the high refractiveindex resin having a relatively low heat resistance is injected to formthe microlens array in the previous step, it may be desirable to use apolyimide alignment film specialized as a type curable at a lowtemperature in the alignment treatment of step S6. However, since manykinds of the recent polyimide resins are curable at relatively lowtemperatures, the polyimide alignment film is not necessarilyspecialized as a type curable at a low temperature. A DLC (diamond likecarbon) film may be used in place of the polyimide alignment film,wherein the DLC film may be subjected to alignment treatment by ionirradiation with specific directivity. Alternatively, a SiOx alignmentfilm formed by obliquely vapor-depositing SiOx may be used in place ofthe polyimide alignment film, wherein alignment of SiOx is obtained byoblique vapor-deposition.

[0255] In the case of using a polyimide alignment film, the polyimidefilm is formed by roll-coating or spin-coating and is subjected torubbing treatment by using a buffing material. In the case of using aDLC alignment film, the DLC film having a thickness of about 5 nm isformed and is subjected to alignment treatment by ion irradiation withspecific directivity. In the case of using a SiO alignment film, the SiOfilm is formed by obliquely vapor-depositing SiO.

[0256] In step S7, the TFT large-sized substrate having the diameter of8 inches is divided into individual single substrates each having a 0.9inch square size, for example, by diving or CO₂ laser cutting. SingleTFT substrates each incorporating a microlens array are thus obtained.

[0257] Subsequently, single counter substrates each incorporating amicrolens array, which have been evaluated as non-defective products,are prepared.

[0258] In step S8, each of the above single counter substrates isoverlapped to one of the single TFT substrates each incorporating amicrolens array, which have been evaluated as non-defective products,with a specific gap kept therebetween, and the gap is filled withcrystal liquid such as nematic liquid crystal through a filling port,followed by sealing of the filling port. To be more specific, a frame ofa seal material having a filling port is formed around a peripheralportion of either the microlens array incorporating TFT substrate or themicrolens array incorporating counter substrate. The microlens arrayincorporating TFT substrate is overlapped to the microlens arrayincorporating counter substrate while alignment marks formed on both thesubstrates are aligned to each other, and the seal material is cured.After the liquid crystal is injected in the gap through the fillingport, the filling port is sealed with a UV-cured type adhesive. Theliquid crystal is heated and rapidly cooled, to adjust alignment of theliquid crystal.

[0259] As described above, according to this embodiment, a large areasubstrate, which is to be divided into a plurality of single substratescorresponding to individual panels, is subjected to the bonding step,polishing step, sticking step, and peeling step, to integrate a largearea microlens array corresponding to a plurality of single microlensarrays, and is divided into single substrates corresponding toindividual panels in a suitable step (step S7). Accordingly, it ispossible to promote rationalization of the production process. In thisembodiment, a TFT large-sized substrate, on which a microlens arraycorresponding to a plurality of single microlens arrays is formed, isdivided into single TFT substrates, and each of the single TFTsubstrates is overlapped to one of previously prepared single countersubstrates, on each of which a single microlens array is formed, with aspecific gap kept therebetween, to obtain a panel (step S8). Inaddition, according to this embodiment, after the base glass is peeledfrom the surface of the TFT large-sized substrate and the TFTlarge-sized substrate is cleaned in the peeling step (step S5), analignment layer for alignment of a liquid crystal layer is formed on theexposed surface of the TFT large-sized substrate (see step S6) in atemperature range not to damage the heat resistance of the microlensarray formed in step S4.

[0260]FIGS. 21A and 21B are typical diagrams showing a concrete dividingmethod used in the dividing step (step S7) shown in FIG. 20. Thedividing method is performed by dividing a large-sized substrate bydicing or CO₂ laser cutting, to prepare microlens array incorporatingsingle TFT substrates each having a specific size.

[0261] As shown in the figures, the method includes two steps. In thefirst step (first dicing) shown in FIG. 21A, a large-sized substrate1007 is partially diced along boundaries, which are defined to partitiona large-sized substrate 1007 into individual panels, by using a V-cutdicing blade 1021, to form V-shaped grooves in cross-section. In thesecond step (second dicing) shown in FIG. 21B, the grooves of thelarge-sized substrate 1007 are perfectly cut by using a general dicingblade 1022, to separate the large-sized substrate into respectivepanels. With these steps, it is possible to obtain single substrateswith tapered end faces.

[0262] By partially dicing the large-sized substrate to form theV-shaped grooves in the large-sized substrate in the first step andfully dicing the large-sized substrate to separate the large-sizedsubstrate into single substrates in the second step, it is possible tochamfer each of the single substrates. The single substrate thuschamfered is advantageous in preventing occurrence of cracking andchipping of an end face of the TFT thin substrate when the TFT substrateis assembled into the panel. In addition, each of the first dicing andthe second dicing may be desirable to be continuously performed by usinga dual dicer.

[0263] A third embodiment of the method of producing a liquid crystaldisplay device according to the present invention will be described withreference to FIG. 22.

[0264]FIG. 22 is a process diagram showing the steps of producing theliquid crystal display device in this embodiment, wherein a multi-chipmodule process is performed in steps S1 to S7 and a single-chip moduleprocess is performed in step S8, with ML counter substrates (single-chipmodule substrates) prepared between steps S6 and S7. This embodiment isdifferent from the previous embodiment shown in FIG. 20 in that theabove-described steps S7 and S8 are reversed to each other. In thisembodiment, in step S7, non-defective single ML counter substrateshaving been subjected to alignment treatment are overlapped to anon-defective ML incorporating TFT large-sized substrate having beensubjected to alignment treatment, to be thus assembled, and liquidcrystal is injected in the gap therebetween and is sealed; and in stepS8, the ML incorporating TFT large-sized substrate is divided, to obtainindividual panels. As compared with the previous embodiment shown inFIG. 20, this embodiment is rational because the multi-chip moduleprocess can be continued immediately before the final step. As describedabove, according to this embodiment, after a microlens arraycorresponding to a plurality of single microlens arrays is formed on aTFT large-sized substrate, single counter substrates, on each of which asingle microlens array is previously formed, are assembled to the TFTlarge-sized substrate (step S7), and the TFT large-sized substrate isdivided, to form individual panels (step S8).

[0265]FIG. 23 is a typical view showing a concrete assembling methodused in the above-described assembling step S7 shown in FIG. 22. Asshown in the figure, non-defective microlens array incorporating singlesubstrates 1017 are overlapped on non-defective portions of themicrolens incorporating TFT large-sized substrate 1007 with specificgaps kept therebetween and are fixed thereto by means of a seal material1008, and liquid crystal 1009 is injected in gaps between both thesubstrates 1007 and 1017 and is sealed.

[0266] To be more specific, after the MLTFT large-sized substrate 10 iscoated with the seal material 1008 of a UV-cured or thermally-curedtype, the ML counter substrates 1017 are positioned to correspondingportions of the MLTFT large-sized substrate 1007 by using alignmentmarks provided therefore and are overlapped thereto with a specific gapskept therebetween, and are fixed thereto by curing the seal material1008 by UV irradiation or heating. The liquid crystal is then injectedin the gaps through filling ports, and the filling ports are sealed by aUV-cured type adhesive.

[0267] After the assembling work in step S7 is thus completed, the MLTFTlarge-sized substrate 1007 is divided into single substrates by dicingor laser cutting. As shown by a dashed line, the MLTFT large-sizedsubstrate 1007 is diced along boundaries of respective panels, to obtainpanels. At this time, to prevent occurrence of cracking or chipping ofan end face of the TFT thin substrate 1007, the dicing is preferablyperformed such that the TFT thin substrate 1007 is partially diced alongthe boundaries by using a V-cut dicing blade, to form V-shaped grooves,and the grooves of the TFT thin substrate 1007 are perfectly cut byusing a general dicing blade, to separate the TFT thin substrate intorespective panels.

[0268]FIGS. 24A and 24B are process diagrams showing one example of themethod of producing the ML counter substrate 1017 shown in FIG. 23.

[0269] As shown in FIG. 24A, a frame of a seal material 1016 is formedaround a peripheral portion of an ML substrate 1014 on which microlensplanes 1014 r are previously formed. A cover glass substrate 1111 isoverlapped to the ML substrate 1014 with a specific gap kepttherebetween. In such a state, the seal material 1016 is cured.

[0270] As shown in FIG. 24B, a high refractive index transparent opticalresin 1015 is injected in a gap between the cover glass substrate 1011and the ML substrate 1014 and is cured by heating, and the gap is sealedby a UV-cured type adhesive. The thickness of the back surface side ofthe cover glass substrate 1011 is reduced by the method for one-surfacepolishing with a grade suitable for optics, to prepare the ML countersubstrate 1017. A transparent conductive film such as ITO is formed overthe polished back surface of the cover glass substrate 1011, to form acounter electrode 1018. A polyimide alignment film 1019 is formed on thecounter electrode 1018, and is subjected to alignment treatment such asrubbing treatment. At this time, the thickness of the ML countersubstrate 1017 may be adjusted to a specific value by polishing the MLsubstrate 1014 and the cover glass substrate 1011 in accordance with amethod for both-surface polishing with a grade for optics. In this case,after the ML substrate 1014 is formed by filling the microlens planes1014 r with a high refractive index transparent resin, a transparentresin film may be formed on the surface, opposed to the microlensplanes, of the resin and further a SiO₂ film be formed thereon bysputtering or vapor-deposition. The formation of such a stacked layerfilm can eliminate the need of provision of the cover glass substrate1014, to reduce the production cost.

[0271] The single ML counter substrates 1017 thus formed are assembledon the multi-chip module type large-sized MLTFT substrate 1007 shown inFIG. 23.

[0272] A fourth embodiment of the method of producing a liquid crystaldisplay device according to the present invention will be described withreference to FIG. 25.

[0273]FIG. 25 shows the steps of producing a liquid crystal displaydevice in this embodiment, wherein a multi-chip module process isperformed in steps S1 to S6 and a single-chip module process isperformed in steps S7 and S8, with ML counter substrates (single-chipmodule substrates) prepared between steps S7 and S8.

[0274] This embodiment is modified from the embodiment shown in FIG. 20.

[0275] In the embodiment shown in FIG. 20, the microlens array made froma high refractive index resin is formed between the TFT large-sizedsubstrate and the ML large-sized substrate in step S4, and a polyimidealignment film is formed on the TFT large-sized substrate and issubjected to alignment treatment in step S6. In these steps, dependingon the heat resistance of the high refractive index resin used for themicrolens array, the polyimide film used for alignment treatment must beselected as a low temperature curable polyimide film.

[0276] On the contrary, in this embodiment, a polyimide film foralignment treatment is first formed in step S2, and then a microlensarray made from a high refractive index resin is formed in step S5. Thepolyimide film for alignment treatment is thus not required to beselected as a low temperature curable polyimide film, but may beselected as a high temperature curable polyimide film excellent inperformance and stability.

[0277] In this way, according to this embodiment, before a series ofsteps, that is, a bonding step, a polishing step, a sticking step, and apeeling step are performed to integrate a microlens array to the backsurface of a TFT large-sized substrate, an alignment step for forming analignment layer used for alignment of a liquid crystal layer on thesurface of the TFT large-sized substrate is performed (step S2).

[0278] A general polyimide resin is curable at a high temperature ofabout 180° C., whereas a general high refractive index transparent resinis curable a low temperature ranging from 60 to 120° C. Accordingly, itis undesirable to form a film made from a general polyimide on the TFTlarge-sized substrate on which a microlens array made from a generalhigh refractive index transparent resin has been mounted. For thisreason, in the embodiment shown in FIG. 20, a low temperature curablepolyimide film or a DLC film is used as an alignment film. On thecontrary, in this embodiment, since an alignment film for alignmenttreatment is formed before a microlens array made from a high refractiveindex resin is formed, a film made from a general polyimide resincurable at a high temperature of about 180° C. can be used as thealignment film.

[0279] A fifth embodiment of the method of producing a liquid crystaldisplay device according to the present invention will be described withreference to FIG. 26.

[0280]FIG. 26 is a process diagram showing the steps of producing aliquid crystal display device in this embodiment, wherein a multi-chipmodule process is performed in steps S1 to S6 and a single-chip moduleprocess is performed in steps S7 and S8, with ML counter substrates(single-chip module substrates) prepared between steps S6 and S7.

[0281] In this embodiment, like the previous embodiment shown in FIG.22, single ML counter substrates are assembled to a MLTFT large-sizedsubstrate and then the MLTFT large-sized substrate is divided intosingle substrates corresponding to individual panels; however, unlikethe previous embodiment shown in FIG. 22, the alignment treatment usingan alignment film is performed in step S2, and then the formation of amicrolens array using a high refractive index transparent resin isperformed in step S5. As a result, like the embodiment shown in FIG. 25,a film made from a high temperature curable polyimide resin can be usedas the alignment film.

[0282] A sixth embodiment of the method of producing a liquid crystaldisplay device according to the present invention will be described withreference to FIG. 27.

[0283]FIG. 27 is a process diagram showing the steps of producing aliquid crystal display device in this embodiment, wherein a multi-chipmodule process is performed in steps S1 to S7 and a single-chip moduleprocess is performed in step S8, with an ML counter large-sizedsubstrate (multi-chip module substrate) prepared between steps S6 andS7.

[0284] According to this embodiment, in step S7, an ML counterlarge-sized substrate is assembled to an MLTFT large-sized substrate,and in step S8, the assembly of the MLTFT large-sized substrate and theML counter large-sized substrate is divided into individual panels.Since both the large-sized substrates are used immediately before thefinal step, the production process is more rationalized. In thisembodiment, however, the selection of whether products are non-defectiveor defective is performed by inspection for single products after thefinal step.

[0285] As described above, according to this embodiment, the ML counterlarge-sized substrate incorporating a microlens array corresponding to aplurality of single microlens arrays is overlapped to the MLTFTlarge-sized substrate incorporating a microlens array corresponding to aplurality of single microlens arrays with a specific gap kepttherebetween, to be assembled into a large-sized panel portioncorresponding to a plurality of panels (step S7), and the assembly isdivided into individual panels (step S8). In addition, according to thisembodiment, the microlens array using a high refractive indextransparent optical resin is formed in step S4, and a low temperaturecurable polyimide film or a DLC film for alignment treatment is formedin step S6.

[0286] A seventh embodiment of the method of producing a liquid crystaldisplay device according to the present invention will be described withreference to FIG. 28.

[0287]FIG. 28 is a process diagram showing the steps of producing aliquid crystal display device in this embodiment, wherein a multi-chipmodule process is performed in steps S1 to S7 and a single-chip moduleprocess is performed in step S8, with an ML counter large-sizedsubstrate (multi-chip module substrate) prepared between steps S6 andS8.

[0288] In this embodiment, like the previous embodiment shown in FIG.27, an ML counter large-sized substrate is assembled to a TFTlarge-sized substrate, and then the assembly is divided into individualpanels; however, unlike the previous embodiment shown in FIG. 27, analignment film for alignment treatment is formed in step S2 and amicrolens array using a high refractive index transparent optical resinis formed in step S5. Accordingly, a general high temperature curablepolyimide film can be used as the alignment film for alignmenttreatment.

[0289] An eighth embodiment of the method of producing a liquid crystaldisplay device according to the present invention will be described withreference to FIG. 29.

[0290]FIG. 29 is a process diagram showing the steps of producing aliquid crystal display device in this embodiment, wherein a multi-chipprocess is performed in step S1 and a single-chip module process isperformed in steps S2 to S8, with ML counter substrates (single-chipmodule substrates) prepared between steps S7 and S8.

[0291] In this embodiment, unlike the previous embodiments, panels areobtained by basically adopting a single-chip module process in place ofa multi-chip module process.

[0292] A TFT large-sized substrate having a diameter of 8 inches isprepared in step S1, and is then divided into TFT single substrates eachhaving a 0.9 inch square size by dicing or CO₂ laser cutting. If needed,the TFT single substrate may be coated with a resist film for protectingthe surface and preventing contamination due to a halogen gas.

[0293] In step S3, a base glass having a 0.9 inch square size is stuckon each of the TFT single substrates. The base glass may be borosilicateglass and the TFT substrate may be made from synthetic quartz glass. Theparallelism of the base glass is accurately finished to 1 to 2 μm. Thebase glass is bonded to the TFT substrate by means of a double-coatedtape of a thermoplastic transparent polymer type or UV-cured typeadhesive or a double-coated tape of a thermosetting type adhesive.

[0294] In step S4, the back surface of the TFT substrate is polished bythe method for one-surface polishing with a grade suitable for optics tobe thinned to a thickness of 20 μm. A variation in thickness of the TFTsubstrate is preferably suppressed within ±3 μm. In step S5, a microlenssubstrate (ML substrate) having a 0.9 inch square size, in whichmicrolens planes are previously formed, is overlapped to the thinned TFTsubstrate, and a high refractive index transparent resin is injected ina gap therebetween and is sealed.

[0295] In step S6, the base glass is peeled from the TFT substrate by,for example, heating, and the TFT substrate is cleaned with an organicsolvent. The peeled base glass, which is highly accurately finished, isre-usable. In addition, the base glass may be peeled and the TFTsubstrate may be cleaned after curing of a seal material by UVirradiation in the subsequent step. In step S7, alignment treatment isperformed by, for example, forming a low temperature curable polyimidealignment film and subjecting the polyimide film to rubbing treatment abuffing material; or forming a DLC film and subjecting the DLC film toion irradiation with directivity.

[0296] In step S8, a single ML counter substrate is overlapped to theMLTFT substrate with a specific gap kept therebetween, and liquidcrystal is injected in the gap and is sealed. To be more specific, aframe of, for example, a UV-cured type seal material is formed on one ofthe substrates, and the other substrate is overlapped thereto with aspecific gap kept therebetween while alignment marks provided thereforeare aligned to each other. The seal material is cured by UV irradiation,to fix both the substrates to each other. An empty panel (in the statebefore being filled with liquid crystal) is thus obtained. Liquidcrystal is injected in the panel via a filling port formed in the sealmaterial and is sealed, to finish a duel microlens array type liquidcrystal display device.

[0297] A ninth embodiment of the method of producing a liquid crystaldisplay device according to the present invention will be described withreference to FIG. 30.

[0298]FIG. 30 is a process diagram showing the steps of producing aliquid crystal display device in this embodiment, wherein a multi-chipmodule process is performed in step S1 and a single-chip module processis performed in steps S2 to S8, with ML counter substrates (single-chipmodule substrates) prepared between steps S7 and S8.

[0299] In this embodiment, like the previous embodiment shown in FIG.29, panels are obtained by basically adopting a single-chip moduleprocess; however, unlike the previous embodiment shown in FIG. 29, analignment film for alignment treatment is formed in step S3, and amicrolens array using a high refractive index transparent optical resinis formed after the ML substrate is stuck on the TFT substrate in stepS6.

[0300] A tenth embodiment of the method of producing a liquid crystaldisplay device according to the present invention will be described withreference to FIG. 31.

[0301]FIG. 31 is a process diagram showing the steps of producing aliquid crystal display device in this embodiment.

[0302] In a preliminary step, an ML counter substrate 1017 obtained byintegrating a microlens array to a first substrate on which a counterelectrode is previously formed is prepared. In an assembling step, thecounter substrate (ML substrate) 1017 integrated with the microlensarray is overlapped to the front surface 1001 f of a TFT substrate 1001on which pixel electrodes and switching devices for driving the pixelelectrodes are previously formed with a specific gap kept therebetween,and liquid crystal is injected in the gap and sealed, to obtain a panel.In a bonding step, a base glass 1002 is bonded to the ML countersubstrate 1017 overlapped to the front surface 1001 f of the TFTsubstrate 1001 by using an adhesive 1003 such as a hot melt basedwater-soluble wax, bees wax, or a cyanoacrylate based adhesive. Theadhesive 1003 may be that obtained by diluting an acrylate with anon-chlorine based organic solvent (acetone, a combination of acetoneand ethanol, or IPA). In a polishing step, in the state being held bythe base glass 1002, the back surface 1001 b of the TFT substrate ispolished. In a sticking step, a microlens array is stuck on the polishedback surface 1001 b of the TFT substrate 1001.

[0303] Unlike the previous embodiments, after a panel is previouslyprepared, the back surface of the TFT substrate is polished and themicrolens array is stuck on the polished back surface of the TFTsubstrate.

[0304] In the production method shown in FIG. 31, since the TFTsubstrate 1001 on which pixel electrodes and thin film transistors arepreviously integrated is polished, it is desirable to take a measureagainst damages due to static electricity.

[0305]FIG. 32 shows an example of the measure against damages due tostatic electricity, wherein a conductive paste 1024 with no residualcoating portion is used as the measure against damages due to staticelectricity. As shown in FIG. 32, a tape, particularly, a conductivepaste tape with no residual coating portion having a thickness nearlyequal to that of the microlens incorporating counter substrate 1017 isprovided in such a manner as to be short-circuited with an outputterminal formed on the TFT substrate 1001, wherein the base glass isfixed to the ML counter substrate 1017 with an adhesive 1003.

[0306]FIG. 33 shows another example of the measure against damages dueto static electricity. As shown in FIG. 33, a connector 1026 composed ofa flexible printed board for external connection is mounted to aconnection terminal of the TFT substrate 1001 by thermo-compressionbonding, and the base glass 1002 is fixed to the ML counter substrate1017 by the adhesive 1003 or a double-coated tape. To stabilize theconnector 1026, a gap between the base glass 1002 and the TFT substrate1001 is filled with the adhesive 1003 or filled with a tape member 1025having a thickness nearly equal to that of the microlens arrayincorporating counter substrate 1017. The connector 1026 may be shortento an extent not to exert adverse effect on polishing of the TFTsubstrate 1001 by the method for one-surface polishing with a gradesuitable for optics in the subsequent step, and the terminal of theconnector 1026 is short-circuited or covered in order not to becontaminated by abrasive or the like. In this way, to take the measureagainst damages due to static electricity, the back surface of the TFTsubstrate 1001 is polished in the state that a plurality of terminalsfor external connection formed on the TFT substrate are kept at the samepotential.

[0307]FIG. 34 is a typical diagram showing the polishing treatment forthe panel shown in FIG. 32. As shown in the figure, the base glass 1002side of the panel is stuck on a work holder 1029 for polishing, and theback surface 1001 b of the TFT substrate 1001 is polished with the baseglass 1002 taken as a reference. To prevent the liquid crystal 1009enclosed in the panel from being heated to a transition temperature ormore, it is desirable to cool the TFT substrate 1001 during polishingthereof by the method for one-surface polishing with a grade suitablefor optics. This makes it possible to keep the alignment state of theliquid crystal 1009, In the example shown in the figure, one-surfacebuffing is performed as the method for one-surface polishing with agrade suitable for optics. The back surface 1001 b of the TFT substrate1001 is pressed to a polishing platen 1027 by applying a specific loadto the TFT substrate 1001. At this time, a specific amount of abrasiveis supplied to the polishing platen 1027.

[0308] To be more specific, the polishing work is performed by rotatingthe polishing platen 1027 such as a tin platen, a vinyl platen, or clothplaten on its axis, constantly dropping a specific amount of a liquidsuch as water, oil, or organic solvent containing abrasive such assilicon carbide, alumina, or diamond on the polishing platen 1027,pressing a workpiece fixed to the work holder 1029 to the polishingplaten 1027 with a specific load applied to the workpiece, and polishingthe surface of the workpiece. The polishing is made in the order oftough polishing, medium polishing, and finish polishing, and theparticle size of the abrasive is correspondingly reduced to graduallyincrease the polishing accuracy. If the amount to be polished is large,the workpiece is thinned to a thickness close to a target thickness byrough-polishing, and is then finished by medium-polishing andfinish-polishing, If the TFT substrate 1001 has a thickness of 800 μm,the substrate 100 is thinned to a thickness of 100 μm by rough-polishingand further thinned to a thickness of 50 μm by medium-polishing, and isfinished to a thickness of 20 μm by finish-polishing. In this case,assuming that the allowance of the thickness of the TFT substrate is20±3 μm, finish polishing is performed while the residual thickness ischecked by an optical or laser type step depth meter with the alignmentmark on the surface of the TFT substrate taken as a reference for eachpolished amount of 10 μm. During such polishing, the panel is notpeeled. This is because the TFT substrate is overlapped to the countersubstrate with a gap of 1 to 3 μm kept therebetween and is fixed theretoby the seal material, and further the spacer is in contact with everypixel.

[0309]FIG. 35 is a typical diagram showing a polishing treatment usingblasting of particles. As shown in the figure, the blasting is performedby preparing a laminar flow of high pressure air in which particles ofabrasives such as silicon carbide, boron carbide, or diamond aredispersed, and blasting a specific amount of the laminar flow from aninjection port at the leading end of a slit-shaped nozzle 1030 whilescanning the nozzle in the reciprocating directions over the backsurface 1001 b of the TFT substrate 1001, to polish the back surface1001 b of the TFT substrate 1001. The blasting is made in the order ofrough blasting, medium blasting, and finish blasting, and the particlesize of the abrasive is correspondingly reduced to gradually increasethe polishing accuracy. If the amount to be polished is large, theworkpiece is thinned to a thickness close to a target thickness byrough-blasting, and is then finished by medium-blasting andfinish-blasting. If the TFT substrate 1001 has a thickness of 800 μm,the substrate 100 is thinned to a thickness of 300 μm by rough-blastingand further thinned to a thickness of 200 μm by medium-blasting, and isfinished to a thickness of 50 μm by finish-blasting.

[0310] Assuming that the allowance of the thickness of the TFT substrateis 20±3 μm, after the TFT substrate is finished to a thickness of 50 μmby finish-blasting, the TFT substrate may be further finished byfinish-buffing performed as the method for polishing with a gradesuitable for optics shown in FIG. 34. The finish polishing is performedwhile the residual thickness is checked by an optical or laser type stepdepth meter with the alignment mark on the surface of the TFT substratetaken as a reference for each polished amount of 10 μm.

[0311]FIG. 36 shows a step of sticking the ML substrate 1004 to the backsurface of the TFT substrate 1001 after the polishing step shown in FIG.34. As shown in the figure, in the state that the base glass 1002, theML incorporating counter substrate 1017, and the TFT substrate 1001 areintegrated with each other, a frame of a seal material 1006 made from aUV-cured type adhesive or a UV-cured/thermal-cured combination typeadhesive is formed around a peripheral portion of the back surface ofthe TFT thin substrate 1001 by dispense-coating of the seal material1006. The ML substrate 1004 is overlapped to the TFT thin substrate 1001with a specific gap kept therebetween while alignment marks providedtherefore are aligned to each other, and the seal material 1006 is curedby UV irradiation. At this time, the focal distance of each microlens isfinely adjusted by the thickness of the seal material 1006. For easyfine adjustment, the seal material 1006 may contain a spacer havingspecific sizes in an amount not to degrade the seal characteristic. Thespace is made from a metal, glass, ceramic, or the like. These materialsmay be used singly or in combination. The material is preferably used inthe form of particles having spherical shapes or fiber shapes.

[0312]FIG. 37 shows a filling step after the sticking step shown in FIG.36. As shown in the figure, a high refractive index transparent opticalresin 1005 is press-injected under vacuum in the gap through a fillingport provided in the frame-shaped seal material 1006 and the fillingport is sealed with a UV-cured type adhesive. While not shown, in thecase of using a cyanoacrylate based adhesive as the adhesive 1003, thecyanoacrylate based adhesive is melted by heating, to peel the baseglass 1002, followed by cleaning of the entire panel with an organicsolvent such as IPA, acetone, a combination of acetone and ethanol, ormethanol. In the case of a hot melt type water-soluble wax as theadhesive 1003, the water-soluble wax is melted by heating, to peel thebase glass 1002, followed by ultrasonic cleaning of the entire panelwith pure water or hot pure water at 50 to 60° C.

[0313]FIG. 36A shows an example that a jig 1002 a is used in place of abase glass for supporting the panel. The jig 1002 a serving as a baseglass is fixed to a work holder 1029 of a polishing platen, Passages1002 b for vacuum attraction are formed in the jig 1002 a and the workholder 1029. The panel obtained by assembling the TFT substrate 1001 tothe microlens array incorporating counter substrate 1017 is polished ina state being fixed by the jig 1002 a. In this case, to prevent damagesdue to static electricity upon polishing, it is desirable toshort-circuit an external connection terminal 1001 t of the TFTsubstrate 1001 to a conductive pad 1002 p provided on the jig 1002 a.

[0314]FIGS. 38B and 38C show an example that LCD panels are fixed to awork holder 1029 of a large-sized polishing platen provided with aplurality of jigs 1002 a serving as base glasses. The ML countersubstrate 1017 side of each panel is set in a recess of the jig 1002 awith the TFT substrate 1001 side directed upwardly and is fixed theretoby vacuum attraction, and in such a state, the back surface of the TFTsubstrate is polished. Even in this case, to prevent damages due tostatic electricity upon polishing, it is desirable to short-circuit anexternal connection terminal of the TFT substrate to a conductive padprovided on the jig 1002 a.

[0315] In general, the synthetic quartz glass as a material of a TFTsubstrate and a counter substrate for a high temperature polysiliconTFTLCD used for a projector is specified to be finished with highaccuracy in terms of surface roughness and dimensions. From thisviewpoint, according to the embodiments shown in FIGS. 31 to 38, thecounter substrate can be used in place of the base glass by sufficientlychecking the film thickness of the counter substrate during polishing,to eliminate the need of provision of the base glass, thereby reducingthe production cost.

[0316]FIG. 39 is a typical sectional view showing a further example of aliquid crystal display device produced according to the presentinvention.

[0317] A microlens array incorporating counter substrate 1017 isoverlapped to a microlens array incorporating TFT substrate 1007 with aspecific gap kept therebetween and is fixed thereto, and liquid crystal1009 is enclosed in a gap therebetween. Here, a microlens arrayintegrated on the back surface of the TFT substrate 1001 thinned bypolishing is configured such that lens planes “r” have a doublestructure. To be more specific, convex lens planes “r” formed on atransparent resin layer 1004 having a refractive index “ng1-2” areoppositely spaced from convex lens planes “r” formed on a transparentresin layer 1004′ having a refractive index “ng2-2” by means of a sealmaterial 1006, and a transparent optical resin 1005 having a refractiveindex “n1” is enclosed therebetween, to form the microlens array. Atthis time, the refractive index “n1” of the transparent optical resin1005 is lower than each of the refractive index “ng1-2” of thetransparent resin layer 1004 and the refractive index “ng2-2” of thetransparent resin layer 1004′. The microlens array incorporating countersubstrate 1017 side has the same configuration, wherein a transparentoptical resin 1015 having a refractive index “n1” is inserted between atransparent resin layer having a refractive index “ng1-1” and atransparent resin layer having a refractive index “ng2-1”.

[0318]FIG. 40 shows an example showing the concrete shape and size of aliquid crystal display device produced according to the presentinvention. An MLTFT substrate 1007 is overlapped to an ML countersubstrate 1017 with a specific gap kept therebetween and is fixedthereto, and liquid crystal 1009 is enclosed in a gap therebetween. Thefocal distance (equivalent value in air) of each microlens on the MLcounter substrate 1017 side is F1=30.699 μm. The microlens has astructure that a transparent resin layer having a refractive index of1.45 is in contact with a transparent optical resin 1015 having arefractive index of 1.66 at a boundary defined by a lens plane 1014 r. Acounter substrate 1011 is made from the crystallized glass “Neo Ceram”and is thinned by polishing. The depth of the lens plane 1014 r is 10.3μm and the counter substrate 1011 is thinned to 20 μm. On the otherhand, the focal distance (equivalent value in air) of each microlensformed on the MLTFT substrate 1007 is F2=41.4 μm (actual distance: 64.6μm). A transparent resin layer having a refractive index of 1.44 is incontact with a transparent optical resin 1005 having a refractive index1.596 at a boundary defined by the lens plane 1004 r, to form themicrolens. A quartz glass 1001 having a refractive index of 1.46 isthinned to 20 μm. As a result, the distance between principal points ofthe microlens functioning as a condenser lens formed on the ML countersubstrate 1017 side and the microlens functioning as a field lens formedon the MLTFT substrate 1007 side is 64.6 μm. In addition, a TFT pixelpitch is 18 μm. The above dimensions are all actual dimensions exceptfor the focal distances.

[0319] As described above, an effect of the present invention is toeliminate the need of provision of a cover glass, which has beenrequired for a microlens array such as a single microlens array (SML) ora duel microlens array (DML), and hence to contribute to thinning of amicrolens array. Another effect is that since a microlens array having aplanarized surface is mounted in a liquid crystal panel, the mechanismstress applied to the microlens array can be reduced Accordingly, thepresent invention is advantageous in producing a microlens array with ahigh efficiency and a high accuracy, and in improving the yield and theperformance of the microlens array.

[0320] A further effect of the present invention is to realize a liquidcrystal display device having a duel microlens array configuration thatone microlens array is disposed on a counter substrate side and theother microlens array is disposed on a TFT substrate side. Such adisplay device is advantageous in improving an effective aperture ratioand the utilization efficiency of light emitted from a light source,thereby enhancing the luminance. A projector, to which the liquidcrystal display device according to the present invention is applied,makes it possible to realize the downsizing of the projector and thecost-reduction of a projection lens.

[0321] Since a TFT large-sized substrate is divided by partially dicingthe TFT large-sized substrate so as to form V-shaped grooves and fullydicing the large-sized substrate at the V-grooves, it is possible tochamfer the single substrates. The single substrate thus chamfered isadvantageous in preventing occurrence of cracking and chipping of theTFT thin, thereby improving the yield and quality. Additionally,according to the present invention, it is possible to prevent damagesdue to static electricity and cracking of a TFT thin substrate uponpolishing of the TFT thin substrate by a method for one-surfacepolishing with a grade suitable for optics, and hence to improve theyield and quality.

[0322] While the preferred embodiments of the present invention havebeen described using the specific terms, such description is forillustrative purposes only, and it is to be understood that changes andvariations may be made without departing from the spirit or scope of thefollowing claims,

What is claimed is:
 1. A method of producing a microlens array,comprising: a patterning step of forming a first optical resin layerhaving a first refractive index on a transparent substrate and forming aplurality of microlens planes arrayed in a two-dimensional pattern onthe front surface of said first optical resin layer; a planarizing stepof forming a planarized second optical resin layer; a joining step ofproviding a support layer on which a transparent protective film ispreviously formed; and a removing step of removing said support layer insuch a manner that only said protective film remains on said secondoptical resin layer; wherein said planarizing step comprises a step offilling irregularities of the microlens planes with a resin having asecond refractive index and planarizing the front surface, opposed tothe microlens planes, of said resin, to form said planarized secondoptical resin layer; and said joining step comprises a step of joiningsaid support layer to said planarized second optical resin layer.
 2. Amethod of producing a microlens array according to claim 1, wherein saidjoining step is performed before said planarizing step; and wherein saidjoining step comprises a step of joining said support layer to themicrolens side of said first optical resin layer with a specific gapkept therebetween; and said planarizing step comprises a step of fillingthe gap with a liquid resin and curing said resin, to form saidplanarized second optical resin layer.
 3. A method of producing amicrolens array according to claim 1, wherein said planarizing stepcomprises: a step of coating the front surface of said first opticalresin layer with a liquid resin by a spin-coating process so as to fillthe microlens planes with said liquid resin and to planarize the frontsurface of said liquid resin, to form said polarized second opticalresin layer.
 4. A method of producing a microlens array according toclaim 1, wherein said planarizing step comprises: a step of supplying aresin on the front surface side of said first optical resin layer tofill the microlens planes with said resin, and pressing the frontsurface, opposed to the microlens planes, of said resin with a stamperhaving a flat plane, to form said planarized second optical resin layer.5. A method of producing a microlens array according to claim 1, whereinsaid protective film is made from SiO₂, SiN, a-DLN, or Al₂O₃.
 6. Amethod of producing a microlens array, comprising: a patterning step offorming a first optical resin layer having a first refractive index on atransparent substrate and forming a plurality of microlens planesarrayed in a two-dimensional pattern on the front surface of said firstoptical resin layer; and a filling/plarizing step of fillingirregularities of the microlens planes with a resin having a secondrefractive index, and planarizing the front surface, opposed to themicrolens planes, of said resin, to form a second optical resin layer;wherein said filling/planarizing step is performed by a spin-coatingprocess.
 7. A method of producing a microlens array, comprising: apatterning step of forming a first optical resin layer having a firstrefractive index on a transparent substrate and forming a plurality ofmicrolens planes arrayed in a two-dimensional pattern on the frontsurface of said first optical resin layer; a filling step of fillingirregularities of the microlens planes with a resin having a secondrefractive index; and a planarizing step of planarizing the frontsurface, opposed to the microlens planes, of said resin filling themicrolens planes, to form a second optical resin layer; wherein saidplanarizing step is performed by planarizing the front surface of saidresin filling the microlens planes by a flat stamping process.
 8. Amethod of producing a microlens array having a double structure,comprising: a first patterning step of forming a first optical resinlayer on a first support and forming two-dimensionally arrayed firstmicrolens planes on the front surface of said first optical resin layer;a first planarizing step of filling irregularities of the firstmicrolens planes with an optical resin having a refractive indexdifferent from that of said first optical resin layer, and planarizingthe front surface, opposed to the microlens planes, of said opticalresin, to form a first microlens array; a second patterning step offorming a second optical resin layer on a second support and formingtwo-dimensionally arrayed second microlens planes on the front surfaceof said second optical resin layer; a second planarizing step of fillingirregularities of the second microlens planes with an optical resinhaving a refractive index different from that of said second opticalresin layer, to form a second microlens array; and a joining step ofjoining the planarized surface of said first microlens array to theplanarized surface of said second microlens array in a state that thefirst microlens planes are aligned to the second microlens planes,thereby integrating said first and second microlens arrays to eachother.
 9. A liquid crystal display device having a panel structurecomprising: a drive substrate on which at least pixel electrodes andswitching devices for driving said pixel electrodes are formed; acounter substrate on which at least a counter electrode is formed; and aliquid crystal layer interposed between said drive substrate and saidcounter substrate joined such that said pixel electrodes are opposed tosaid counter electrode with a specific gap kept therebetween; wherein amicrolens array composed of microlens arrayed in a two-dimensionalpattern corresponding to an array pattern of said pixel electrodes isassembled at least to said counter substrate; and wherein said microlensarray has the back surface joined to said counter substrate and thefront surface planarized; and said counter electrode is formed on theplanarized front surface of said microlens array via a protective film.10. A liquid crystal display device according to claim 9, wherein aftersaid protective film previously formed on a support is bonded on theplanarized front surface of said microlens array, said support isremoved to expose said protective film, and said counter electrode isformed on said exposed protective film.
 11. A liquid crystal displaydevice according to claim 9, wherein said protective film is made fromAl₂O₃, a-DLC, TiO₂, TiN, or Si.
 12. A liquid crystal display deviceaccording to claim 9, wherein said microlens array has a doublestructure including first microlenses functioning as condenser lensesdisposed on the side apart from said liquid crystal layer and secondmicrolenses substantially functioning as field lenses disposed on theside close to said liquid crystal layer; and the distance between aprincipal point of each of said second microlenses and said liquidcrystal layer is set to a value in a range of 10 μm or less.
 13. Aliquid crystal display device having a panel structure comprising: adrive substrate on which at least pixel electrodes and switching devicesfor driving said pixel electrodes are formed; a counter substrate onwhich at least a counter electrode is formed; and a liquid crystal layerinterposed between said drive substrate and said counter substratejoined such that said pixel electrodes are opposed to said counterelectrode with a specific gap kept therebetween; wherein a microlensarray composed of microlens arrayed in a two-dimensional patterncorresponding to an array pattern of said pixel electrodes is assembledat least to said drive substrate; and wherein said microlens array has astacked structure of a first optical resin layer having a firstrefractive index and a second optical resin layer having a secondrefractive index; said first optical resin layer has microlens planesarrayed in a two-dimensional pattern, and said second optical resinlayer is formed to fill irregularities of the microlens planes and has aplanarized front surface opposed to the microlens planes; and saidmicrolens array is assembled to said drive substrate in such a mannerthat the planarized surface of said second optical resin layer of saidmicrolens array is joined to the back surface of said drive substrate.14. A liquid crystal display device according to claim 13, wherein saidmicrolens array is formed by joining said first optical resin layer to asupport layer having a protective film previously formed thereon with aspecific gap kept therebetween, filling the gap with a liquid resin andcuring said liquid resin to form said second optical resin layer, andremoving said support layer to expose said protective film, the exposedsurface of said protective film being taken as the planarized surface ofsaid second optical resin layer.
 15. A liquid crystal display deviceaccording to claim 13, wherein said microlens array is formed by fillingthe microlens planes of said first optical resin layer with a resin, andpressing the front surface, opposed to the microlens planes, of saidresin with a stamper having a flat plane, to planarize the front surfaceof said second optical resin layer.
 16. A liquid crystal display deviceaccording to claim 13, further comprising: a microlens array disposed onsaid counter substrate in such a manner as to be aligned to saidmicrolens array disposed on said drive substrate; wherein one of saidmicrolens arrays functions as condenser lenses and the other functionsas field lenses.
 17. A liquid crystal display device according to claim13, wherein said drive substrate is thinned by polishing the backsurface thereof, and the planarized surface of said second optical resinlayer of said microlens array is joined to the polished back surface ofsaid drive substrate.
 18. A projector comprising: a light source foremitting light; a liquid crystal display device having a function ofoptically modulating incident light; and a projection lens forprojecting light modulated by said liquid crystal display device; saidliquid crystal display device having a panel structure comprising: adrive substrate on which at least pixel electrodes and switching devicesfor driving said pixel electrodes are formed; a counter substrate onwhich at least a counter electrode is formed; and a liquid crystal layerinterposed between said drive substrate and said counter substratejoined such that said pixel electrodes are opposed to said counterelectrode with a specific gap kept therebetween; wherein a microlensarray composed of microlens arrayed in a two-dimensional patterncorresponding to an array pattern of said pixel electrodes is assembledat least to said counter substrate; and wherein said microlens array hasthe back surface joined to said counter substrate and the front surfaceplanarized; and said counter electrode is formed on the planarized frontsurface of said microlens array via a protective film.
 19. A projectorcomprising: a light source for emitting light; a liquid crystal displaydevice having a function of optically modulating incident light; and aprojection lens for projecting light modulated by said liquid crystaldisplay device; said liquid crystal display device having a panelstructure comprising: a drive substrate on which at least pixelelectrodes and switching devices for driving said pixel electrodes areformed; a counter substrate on which at least a counter electrode isformed; and a liquid crystal layer interposed between Said drivesubstrate and said counter substrate joined such that said pixelelectrodes are opposed to said counter electrode with a specific gapkept therebetween; wherein a microlens array composed of microlensarrayed in a two-dimensional pattern corresponding to an array patternof said pixel electrodes is assembled at least to said drive substrate;and wherein said microlens array has a stacked structure of a firstoptical resin layer having a first refractive index and a second opticalresin layer having a second refractive index; said first optical resinlayer has microlens planes arrayed in a two-dimensional pattern, andsaid second optical resin layer is formed to fill irregularities of themicrolens planes and has a planarized front surface opposed to themicrolens planes; and said microlens array is assembled to said drivesubstrate in such a manner that the planarized surface of said secondoptical resin layer of said microlens array is joined to the backsurface of said drive substrate.
 20. A method of producing a liquidcrystal display device having a panel structure including: a firstsubstrate having the front surface on which at least pixel electrodesand switching devices for driving said pixel electrodes are formed andthe back surface opposed to the front surface; a second substrate havingthe front surface on which at least a counter electrode is formed andthe back surface opposed to the front surface; and a liquid crystallayer interposed between said first and second substrates joined suchthat said pixel electrodes are opposed to said counter electrode with aspecific gap kept therebetween; wherein a first microlens array composedof two-dimensionally arrayed microlenses for individually condensinglight to said pixel electrodes is integrally formed on one of said firstand second substrates; and a second microlens array composed oftwo-dimensionally arrayed microlenses for allowing light individuallycondensed to said pixel electrodes to pass therethrough is integrallyformed on the other of said first and second substrates; said methodcomprising: a bonding step of bonding a base plate to the front surfaceof each of said first and second substrates; a polishing step ofpolishing the back surface of said substrate in a state that saidsubstrate is held by said base plate, to reduce the thickness of saidsubstrate; a sticking step of sticking the corresponding one of saidfirst and second microlens arrays to the polished back surface of saidsubstrate via a transparent optical resin having a refractive indexhigher or lower than that of said substrate; and a peeling step ofpeeling said base plate from the front surface of said substrate andcleaning said substrate, thereby integrating said correspondingmicrolens array to the back surface of said substrate.
 21. A method ofproducing a liquid crystal display device according to claim 20, furthercomprising a dividing step of dividing, if at least one of said firstand second substrates is a multi-chip module substrate having an areacorresponding to a plurality of panels, said multi-chip module intosingle substrates corresponding to individual panels; wherein after aplurality of the corresponding ones of said first and second microlensarrays, which correspond to the plurality of panels, are integrated tosaid multi-chip module substrate by said bonding step, polishing step,sticking step, and peeling step, said multi-chip module substrate isdivided into single substrates corresponding to individual panels at asuitable stage.
 22. A method of producing a liquid crystal displaydevice according to claim 21, wherein one of said first and secondsubstrates is a multi-chip module substrate having an area correspondingto a plurality of panels and the other is a single-chip modulesubstrate; and wherein a plurality of the corresponding ones of saidfirst and second microlens arrays, which correspond to the plurality ofpanels, are formed on said multi-chip module substrate; said multi-chipmodule substrate is immediately divided into single substratescorresponding to individual panels in said dividing step; saidsingle-chip module substrates to each of which the corresponding one ofsaid first and second microlens arrays is previously integrated areprepared; and said single substrates divided from said multi-chip modulesubstrate are overlapped to said single-chip module substrates inone-to-one relationship with a specific gap kept therebetween, to beassembled into individual panels.
 23. A method of producing a liquidcrystal display device according to claim 21, wherein one of said firstand second substrates is a multi-chip module substrate having an areacorresponding to a plurality of panels and the other is a single-chipmodule substrate; and wherein a plurality of the corresponding ones ofsaid first and second microlens arrays, which correspond to theplurality of panels, are formed on said multi-chip module substrate;said single-chip module substrates to each of which the correspondingone of said first and second microlens arrays is previously integratedare prepared; said single-chip module substrates are assembled to saidmulti-chip module substrate; and said multi-chip module substrateassembled with said single-chip module substrates is divided intoindividual panels in said dividing step.
 24. A method of producing aliquid crystal display device according to claim 21, wherein one of saidfirst and second substrates is a multi-chip module substrate to which aplurality of the corresponding ones of said first and second microlensarrays for a plurality of panels are integrated, and the other of saidfirst and second substrates is also a multi-chip module substrate towhich a plurality of the others of said first and second microlensarrays for a plurality of panels are integrated; and wherein saidmulti-chip module substrates are overlapped to each other with aspecific gap kept therebetween, to be assembled into a panel basecorresponding to the plurality of panels; and said panel base is dividedinto individual panels in said dividing step.
 25. A method of producinga liquid crystal display device according to claim 21, wherein saiddividing step comprises: a first dicing step of partially cutting saidmulti-chip module substrate along boundaries defined to partition saidmulti-chip module substrate into individual panels by first dicing, toform grooves having V-shapes in cross-section; and a second dicing stepof perfectly cutting said grooves by second dicing, thereby formingsingle substrates with chamfered end faces.
 26. A method of producing aliquid crystal display device according to claim 20, further comprising:an alignment step of forming, after peeling said base plate from thefront surface of said substrate and cleaning said substrate in saidpeeling step, an alignment layer for aligning said liquid crystal layeron the exposed front surface of said substrate in such a temperaturerange as not to impair the heat resistance of said microlens arrayintegrated to said substrate.
 27. A method of producing a liquid crystaldisplay device according to claim 20, further comprising: an alignmentstep of forming an alignment layer for aligning said liquid crystallayer on the front surface of said substrate; wherein said alignmentstep is performed before said microlens array is integrated to the backsurface of said substrate by said bonding step, polishing step, stickingstep, and peeling step.
 28. A method of producing a liquid crystaldisplay device according to claim 20, wherein said polishing step isperformed by one or a combination of two or more of buffing with a gradesuitable for optics, particle blasting, chemical-mechanical polishing,and chemical etching.
 29. A method of producing a liquid crystal displaydevice according to claim 20, wherein in said polishing step, thethickness of said substrate is reduced by polishing the back surface ofsaid substrate in such a manner that the focal point of each ofmicrolenses of said second microlens array functioning as field lensescorresponds to a principal point of each of microlens of said firstmicrolense array functioning as condenser lenses at the time ofassembling said first and second substrates into a panel.
 30. A methodof producing a liquid crystal display device according to claim 20,wherein said sticking step comprises: a step of preparing said microlensarray composed of microlens planes arrayed in a two-dimensional patternby processing an optical glass material having a relatively lowrefractive index; and a step of positioning said microlens array to thepolished back surface of said substrate, overlapping said microlensarray thereto with a specific gap kept therebetween, filling the gapwith a transparent optical resin having a refractive index higher orlower than that of said substrate, and curing the transparent opticalresin.
 31. A method of producing a liquid crystal display deviceaccording to claim 30, wherein said sticking step comprises: a step offixing the polished back surface of said substrate to said microlensarray with a specific gap kept therebetween by a seal material, fillingthe gap with a transparent optical resin having a refractive indexhigher or lower than that of said substrate, and sealing the gap.
 32. Amethod of producing a liquid crystal display device according to claim30, wherein the microlens planes are formed into spheric, aspheric, orFresnel shapes.
 33. A method of producing a liquid crystal displaydevice according to claim 20, further comprising: a cleaning step ofcleaning said base plate peeled as a spent product in said peeling stepin order to reuse said base plate.
 34. A method of producing a liquidcrystal display device according to claim 20, further comprising: apreliminary step of integrating the corresponding one of said first andsecond microlens arrays to said second substrate; and an assembling stepof assembling said second substrate integrated with said microlens arrayto the front surface of said first substrate; wherein said bonding stepcomprises a step of bonding said base plate to the front surface side ofsaid second substrate assembled on the front surface of said firstsubstrate; said polishing step comprises a step of polishing the backsurface of said first substrate in a state that said panel is held bysaid base plate; and said sticking step comprises a step of sticking thecorresponding one of said first and second microlens arrays to thepolished back surface of said first substrate.
 35. A method of producinga liquid crystal display device according to claim 34, wherein saidpolishing step comprises: a step of polishing the back surface of saidfirst substrate in a state that a plurality of terminals for externalconnection formed on said first substrate are kept at the samepotential.
 36. A method of producing a liquid crystal display deviceaccording to claim 34, wherein said bonding step comprises: a step ofmounting said second substrate side of said panel to said base platefixed to a polishing platen used for said polishing step.